Hi
Give o2 a call on 202 and ask their customer services what the cost would be.
Please try out alternative Networks by their Payg SIM cards to ensure they give you good signal where you live , work and commute before committing to a contract.
Dont rely on any online coverage checkers.
I was interested in giffgaff a while ago which run off o2's Network but their data speeds lagged for me so it's even worth checking any virtual ones that run off o2 also from my own experience.
Good luck and remember you can take your mobile number with you to any new network. Ask for a PAC Code and give that code to your new network. Once the new network uses that code this will cancel your o2 Network.
More here :
http://community.o2.co.uk/t5/Discussions-Feedback/Obtaining-a-PAC-Code-from-the-O2-Network/m-p/54427...Help on cancelling :
http://community.o2.co.uk/t5/Pay-Monthly-and-Pay-Go/Cancelling-Your-Contract-A-Guide/m-p/566774/high...Don't cancel any o2 Direct Debit for a few months after your final bill just in case so you don't end up with a default if o2 try to take another payment and have to deal with the mess this causes with them chasing you for payment and possibly debt collectors and default markers on your credit file in the extreme circumstances.
I wish you well.
