you can get an adsl modem cheaper than £60, check out
www.dabs.com,
www.ebuyer.com, uk.insight.com for cheaper modems.
I think finding the cheapest adsl provider that you can is the best that you can do.
My g/f has a bt line, i think she has option 1 which means any off peak calls to any number 01 or 02 are charged at 6p for the first hour, then just hang up and redial. This should be a good option for you.
Hope this helps!