My current prescription is -5.75/ -5.25 with around 1.5D astigmatism and all other parameters normal. I've had a stable prescription for about 8 years now. Stability is something you will be asked about and it's something to track. Before age 22, my eyes got worse every time I went to the optician (my parents are both pretty short-sighted) but things settled down after that. This is normal.
FMF - as you see you are about as blind as I am, so if you have nothing else wrong, I would expect you will be granted a Class 1 with a deviation.
K-130. They used to give me all the excuses about distortion at high lens powers, poor peripheral vision, losing glasses etc etc. While those arguments may have held water when we all flew Tiger Moths, modern lens (contacts too) technology has solved most of this and the rest is a load of b**ks anyway.
I would suggest to anyone that they contact the CAA medics. They are helpful (i.e. they want to give you a medical if they reasonably can) and are used to eyesight enquiries. They will advise on the best course of action - in my case they said 'come for an initial class 1. We'll do your eyes first and if you fail, you'll only pay for that bit'. Can't say fairer than that.