Fibre Optics and Contracts

Hello everyone, I hoped you'd be able to help out my question.

I've recently been looking to change our broadband provider. After looking at all the options, I decided that O2 provided the best value for money especially as I'm already an O2 customer.

However, I read about the fourthcoming fibre optic improvements and wondered is it was wise to switch from pay monthly to a 12 month contract? I don't know much about these improvements I have to admit. I was concerned that the if the line was improved and I was locked into a contract I might not see the benefits, relative to any other new deals.

I'll probably just give up and blindly switch in the end. Broadband deals seem overwhelming. =/

Many thanks,
Alex