First off, you need more slots in your heals, particularly warmth. I'd six slot both of them with 3 heal, 3 recharge to be honest as, warmth in particular, you want to be able to spam when required.
For PvP purposes, drop health for hurdle. I cringe everytime I see a squishy with health as people just don't seem to realise how feeble it is. Take a look in hero builder and look at how low the regen benefit you're actually getting from it is and you'll see that it really is a completely wasted power whereas hurdle at least gives you unsurpressed movement.
If the build is for teaming, rather than solo, I'd drop fire breath, take some of the other powers a little earlier and get hasten in there and 3 slotted ASAP. That would also open SS up as a travel power at 14 as TP is not the greatest of travel powers for PvP.
I have a lvl 43 fire/thermal designed purely for team support and I'll post his build here when I get home. Thermal wise, I've taken pretty much everything and from fire blast I took fire blast, aim, blaze, blazing bolt and inferno. Pool wise, I took hasten, SS, TP friend, TP(taken quite late though), swift, hurdle stamina, stealth.
Like you, I suffer from knockback and have toyed with taking the leaping pool over TP or concealment but the ability to TP and rez people is too useful and the invisibility stealth offers with SS in PvE is also too useful.
When I get my build up, worth noting that it is a PvE build, rather than PvP so there are a couple of things you may want to consider when comparing it. You'll definitely want Thaw earlier than I have it for PvP purposes and range in your single target heal and shields is normally useful for PvP as well.
My build has also been planned out up to lvl 50 with the Scirroco pool. Power Sink really does help with my end management hugely in PvE as this was the one problem area for me.
There's also a thread on a mixed PvE/PvP build for Fire/Thermal HERE and the last build in there is pretty spot on
Thanks for the advice, it has widened my eyes for new power choices. Yes I'll be dropping Fire Breath, it certainly isn't really useful, took it only because it had somewhat decent damage to be in an attack chain.
Slotting the heals for 3 heals and 3 recharges hasten included sounds like endurance dropping really fast. I'd slot them with 3 Heals, 2 Recharges and 1 EndRedux when I get more slots.
[ QUOTE ]
TP is not the greatest of travel powers for PvP.
[/ QUOTE ]
It's the second greatest IMHO. To add, a Spines Scrapper got angry at me and told me to use leaping like everyone else so I can be impaled with more effect. TP is just something I do not want to not leave with this 
Putting range in heals was pretty yawn to me, but on Thaw it's a damn good idea, or at least better than an endredux in a power which has a small cost. I am almost always out of range when someone says "held 3" and I press my bind for Thaw.
/bind numpad3 "team_select 3$$powexec_name Thaw" (that's for the team member nr. 3)
Decided to go on with Black Scorpion patron, as his Defense-based shield stacked with Vengeance would be like a semi-elude or something similar.
I was sure that someone would comment on my Sniper attack's slotting, which has 2 interrupts. Those two enhancements give me the chance to use it even in the heat of a battle 
Played around a little in the builder and made a build for 50:
---------------------------------------------
Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder - (http://sherksilver.coldfront.net/index.php)
---------------------------------------------
Name:
Level: 50
Archetype: Corruptor
Primary: Fire Blast
Secondary: Thermal Radiation
---------------------------------------------
01) --> Fire Blast==> 3Dmg 2Acc 1Rechg
01) --> Warmth==> 3Heal 2Rechg 1EndRdx
02) --> Fire Shield==> 3DmgRes
04) --> Cauterize==> 3Heal 2Rechg 1EndRdx
06) --> Swift==> 1Run
08) --> Recall Friend==> 1EndRdx
10) --> Plasma Shield==> 3DmgRes
12) --> Aim==> 2Rechg 2TH_Buf
14) --> Teleport==> 2EndRdx
16) --> Hurdle==> 1Jump
18) --> Blaze==> 3Dmg 2Acc 1Rchg
20) --> Stamina==> 3EndMod
22) --> Thaw==> 1Range
24) --> Assault==> 2EndRdx
26) --> Blazing Bolt==> 3Dmg 1Acc 2IntRdx
28) --> Forge==> 2Rchg
30) --> Tactics==> 1EndRdx 2TH_Buf
32) --> Inferno==> 3Dmg 1Acc
35) --> Heat Exhaustion==> 3Acc 2Rchg
38) --> Melt Armor==> 3Acc 2Rchg 1DefDeBuf
41) --> Scorpion Shield==> 3DefBuf 3EndRdx
44) --> Web Cocoon==> 3Hold 2Acc 1Rchg
47) --> Summon Disruptor==> 3Dmg 2Acc
49) --> Vengeance==> 3DefBuf
---------------------------------------------
[ QUOTE ]
/bind numpad3 "team_select 3$$powexec_name Thaw" (that's for the team member nr. 3)
Played around a little in the builder and made a build for 50:
---------------------------------------------
Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder - (http://sherksilver.coldfront.net/index.php)
---------------------------------------------
Name:
Level: 50
Archetype: Corruptor
Primary: Fire Blast
Secondary: Thermal Radiation
---------------------------------------------
01) --> Fire Blast==> 3Dmg 2Acc 1Rechg
01) --> Warmth==> 3Heal 2Rechg 1EndRdx
02) --> Fire Shield==> 3DmgRes
04) --> Cauterize==> 3Heal 2Rechg 1EndRdx
06) --> Swift==> 1Run
08) --> Recall Friend==> 1EndRdx
10) --> Plasma Shield==> 3DmgRes
12) --> Aim==> 2Rechg 2TH_Buf
14) --> Teleport==> 2EndRdx
16) --> Hurdle==> 1Jump
18) --> Blaze==> 3Dmg 2Acc 1Rchg
20) --> Stamina==> 3EndMod
22) --> Thaw==> 1Range
24) --> Assault==> 2EndRdx
26) --> Blazing Bolt==> 3Dmg 1Acc 2IntRdx
28) --> Forge==> 2Rchg
30) --> Tactics==> 1EndRdx 2TH_Buf
32) --> Inferno==> 3Dmg 1Acc
35) --> Heat Exhaustion==> 3Acc 2Rchg
38) --> Melt Armor==> 3Acc 2Rchg 1DefDeBuf
41) --> Scorpion Shield==> 3DefBuf 3EndRdx
44) --> Web Cocoon==> 3Hold 2Acc 1Rchg
47) --> Summon Disruptor==> 3Dmg 2Acc
49) --> Vengeance==> 3DefBuf
---------------------------------------------
[/ QUOTE ]
I use a similar bind, but don't bind thaw to the select button. I use the following, that might be of use to you:
/bind numpad1 "team_select 1"
/bind numpad0 "powexec_name Cauterise"
/bind lshift+numpad0 "powexec_name Thaw"
/bind numpadenter "powexec_name Fire Shield"
/bind lshift+numpadenter "powexec_name Plasma Shield"
With those, selecting and firing off the appropriate single target heal, buff or shield is really fast - highly recommended for all /thermal players.
The build looks pretty good - I use the same slotting for the snipe on my rad/dark, works very well.
Since I7 granted a freespec, and I decided to either use it or save it for later mistakes. This build is level 37 at the moment, removed the numbers and added commas. This build is definately for teaming, both in PvE and PvP. Knockback is my weak spot (ARRR!)
---------------------------------------------
Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder - (http://sherksilver.coldfront.net/index.php)
---------------------------------------------
Name:
Level: 38
Archetype: Corruptor
Primary: Fire Blast
Secondary: Thermal Radiation
---------------------------------------------
01) --> Fire Blast==> Acc, Acc, Dmg, Dmg, Dmg, Rechg
01) --> Warmth==> Heal, Heal, Heal, Rechg, EndRdx
02) --> Fire Shield==> DmgRes, DmgRes, DmgRes
04) --> Cauterize==> Heal, Heal, Heal, Rechg, EndRdx
06) --> Swift==> Run
08) --> Fire Breath==> Acc, Acc, Dmg, Dmg, Dmg, Rechg
10) --> Recall Friend==> EndRdx
12) --> Plasma Shield==> DmgRes, DmgRes, DmgRes
14) --> Teleport==> EndRdx
16) --> Health==> Heal
18) --> Blaze==> Acc, Acc, Dmg, Dmg, Dmg, Rechg
20) --> Stamina==> EndMod, EndMod, EndMod
22) --> Aim==> TH_Buf, TH_Buf, Rechg, Rechg
24) --> Thaw==> Rechg
26) --> Blazing Bolt==> Dmg, Dmg, Dmg, Acc, IntRdx, IntRdx
28) --> Forge==> Rechg, Rechg
30) --> Assault==> EndRdx
32) --> Inferno==> Dmg, Dmg, Dmg, Acc
35) --> Heat Exhaustion==> Acc, Acc, Rechg
---------------------------------------------
Didn't pick Fire Ball because for me it caused too much aggro, oddly Fire Breath doesn't cause me that.
I picked TP because people like it on PvP-areas such as Siren's Call when I TP them to me and use Cauterize and other buffs.
Picked Swift over Hurdle because many teleporters take that, so it's just jumping into a bandwagon.
Didn't 3-slot Aim with recharge because the third recharger reduces the time for about 6 seconds. Put a tohit instead.
Inferno is never used without Aim so I put only 1 accuracy there, and it seemed really accurate even without.
What do you think? Hope it's not gimp, but even if it is, you guys can fix it!