Go on some comparison sites usual suspects and they will give you a league table. NB though that the APR will be representatitve which will mean that around half of the people applying will get a higher rate so beware. Nationwide do a "soft" credit check so you can see your rate before you apply without leaving a footprint on your credit file but I am not sure if this goes up to £100k.
You can tell what I've been doing recently can't you!