The first thing i would do is ring your current lender to see what they will offer you. I would tend to look at a deal without any fees due to the fact you have such a low mortgage remaining. I wouldn't expect bradford and bingley to be able to offer you anything very competitive due to the situation the company are in, but this wont effect the mortgage payments too much as they are based on such a small loan amount.
If you aren't happy with what they can offer, somebody like, dare i say it, northern rock will offer a very competitive 5 year fixed rate with no fees attached at all. It wouldn't hurt you to talk to a broker though, after you've been offered something from bradford and bingley though.
I would also try to sort it ASAP as unfortunately it looks like rates are on their way back up with quite a few lenders.
Michael