In England for 2.5 months - calling home?

The internet may not be up to Skype standards but I'll bet a Magic Jack will work fine. You could then have a US phone number if friends/family want to contact you without toll charges. I think you'd have to sign up for a year. With all the charges, it will run a little over $100. You'd have to bring a phone to use. Cell phone rates are pretty high. You might be better off using a US purchased phone card. I have a Mobal phone but I only use it to call B&Bs if there are problems. It's $1.50 / minute calling out to the US but free in coming in UK. Incoming calls are $1.25/ min in Ireland. Check all the options.

If the pipe isn't big enough where you will be there are plenty of places in Cambridge where it is - I was in a Starbucks near Great St Mary on Sunday which seemed to have plenty of pipe. I'd find a place in the centre from which you could Skype.

Talk to the guys at CPW about your calling needs, they are pretty good at finding you the best deal from the mainstream providers. Once you have used the call time have a look at replacing the SIM with one from these folks. http://www.lebara-mobile.co.uk/prepay/rates

Yes, get a UK prepaid. You'll want it for local calls anyway but check out the rates for calling to the states. They aren't great but they are better than some. Teach the folks back home how to use Skype. They can then make incoming calls to you that won't cost you. You may need to coordinate the calling by making a short call home or sending a text letting them know they can call you now. You might also want a UK prepaid so you can get data on your phone.