If i borrowed £120,000 over 25 years what would be the best repayment mortgage i can expect

I think this is more of a case of who will lend to you, rather than the best deal. I recently took out a new mortgage (in December). HSBC where offering the best rates at the time, however because I didn't bank with them they made it nigh on impossible to borrow from them.
In the end I went to my own bank, even then it wasn't easy. The amount of evidence I had to supply was insane (proof of savings for the deposit, wage slips, credit reports) even though I've been with them for over 20 years! Don't even get me started on the complications if I wanted a joint mortgage with my partner!

To be fair the amount of percentage difference in the overall rate wasn't that big a deal. In my research it seemed most of the banks are offering comparable rates.