Has anybody had this, and is it a reliable indicitor for SFN?

I have a host of SFN-like symptoms which are slowly but surely getting worse. Had two NCV/EMG tests and a fair amount of other tests, all negative. I do have quite severe auto-immune hypothyroidism which I'm being treated for but I'm still not stablilised on a dose.

Anyway, I had requested a skin biopsy but getting one of those is virtually impossible here in the UK, so instead they're giving me thermal threshold testing - which in itself was pretty difficult to get. Am I finally going to get some sort of neuropathy diagnosis?