at Bristol Filton you have aeros (they have a commercial training establishment at Gloucestershire Airport) - but the brance at Filton is used as a PPL school. - dont know much about them, but the guys at Gloucestershire were pretty good.
At Bristol Intl you have Bristol Aviation (who can offer PPL training all the way through to multi IR) - good bunch there, I recommend them.
Next door to them there is the Bristol and Wessex Flying Club, again, friendly bunch. (dont know much on their costs tho)
Nice part of the country to be flying in tho, I miss it!