I have no knowledge on how this best works out but after a little searching I found this.
click here but watch out the cheapest prices may be for three months only, check the (price plan) it could triple in cost there after.
You will have to enter your post code to find out whose service you can connect to as to where she lives.
I suppose if your mobile phone has a good reception on a given network that's a good start to choose from.
I will stand to be corrected here so wait until you get further advice from others in the Helproom and use this way to connect to the Internet.