my iphone has a worn back case and a sticky button

anyone got any experience of these repair places, such as http://www.i-phone-repairs.co.uk/

?

do you think this will polish out?

Apple store.

@ LMT – 140 for a new plastic back, maybe not

Try the DIY guides here:
http://www.ifixit.com/

If you're feeling confident you can fix pretty much anything and get (probably fake but acceptable quality) parts from ebay or original parts from their website.

I replaced the home button on mine yesterday without any problems – Apple quoted 199 dollars, I did it for 3.50 off ebay… The back on my one has a crack in it, so that's next on the list.

Do get the tool kit off ebay tho (has 'spludgers' and also a couple of other useful tools).