Pay as you go mobile & internet for 2 weeks

I have a Japanese friend coming to London for 10 days, she comes every year, and she would like to set up mobile and internet access. Her Japanese phone is locked and she has an iTouch.

I'm on Virgin so we think it might be best if she buys a cheap Virgin Pay As You Go phone with SIM card since she will get included free calls and SMS messages to my Virgin phone. But we're not sure what to do about internet access?

One solution is getting a portable router for her iTouch, she can also use it in the countryside in Japan. Do you put a SIM card into the mobile router like you do a mobile phone? In which case we need to find a provider that can give us a Pay as you go SIM card for internet use that she can use for just 2 weeks and preferably keep the account open for each year.

Virgin have a data bundle which is 5 pounds for 1GB of data. So long as you leave at least 5 pounds in the account they will keep it open indefinitely.

Okay she has bought an unlocked Three MiFi in Japan with a separate SIM card deal so it looks like all we have to do is buy a data SIM card here for the two weeks. Amazon seem to have good deals.