A good practice amp for under £70? Um, youre going to really struggle.

Just save your money cos you'll only end up with something shit which you'll want to replace after about a fortnight
Well, I've heard some good things about the Peavey Vypyr 15. Maybe a Fender Frontman 25R. I don't have that much experience with practice amps, honestly.

I have a Roland Cube 20x, and I find it fairly good. It has some fun effects, and its sound is way better than my brother's Line 6 Spider IV 15. Try looking at a few amps about the 100£ on GAK or Thomann.de(the page is in english too). Laney LG20R, Linebacker LR5 or LX20R perhaps? Try looking at some videos of practice amps, and choose the one you like.
If your only going to use it for practice you might as well look into VST amplifiers such as guitar rig, pod farm (the GX is an absolute steal if you want to just practice), amplitube etc. Most of these come with interfaces already and minimal latency.

A practice amp just won't do anything useful at that price and hey, at least with these you'll be able to use headphones and not disturb the neighbours at half past midnight