I should have put this in my previous post, but you know you can get all the condoms and lube you want from your GUM clinic for free? And a cheapo phone from Tesco with a tenner's worth of credit could be had for under twenty quid not that long ago, although I haven't looked recently I admit. Even if you bin it after a month and get a better one it'll do for now. Ebay is good too, if you use it.
EDIT: Actually it never hurts to have a few spare/old phone handsets knocking about - I've just realised I have four (that still work, anyway) and they all come in useful sometimes.