Keratherm...

I don't suppose anyone has 2x keratherm pads cut for the to-247 package (like on the diyaudio store) that I could buy from them? Really in the UK, can't see it being worthwhile from anywhere else.

Just made an oversight when I bought a pack of 10, when I need 12...

Rapid does have small sheets that I can buy, but it is £25 delivered and they are on back order.
 
both are looking squishy siliconish to me, so no good

kapton is simply not good enough, at least in my experience

now- if not keratherm, then either mica or Alumina oxide pads/blocks (that better than mica)

remember - it's much cheaper taking "expensive" parts and using your amp for years, than taking "whatever is easy" and using it just for short time

it's simply always like that - what you took as minimal proper choice - with struggle to conduct your choices
 
Perfect, thanks. 25 Alumina pads ordered from eBay for not a lot (<£10)!

Kapton has been "just about" good enough. I think I have it at about 90-95% of recommended bias at a "sensible" device temperature. I was going to change it, but never did bother... I agree it's not recommended though!