Unfortunately, as you are most probably aware, Bristol are a distance learning only school. I don't know if they have any plans on starting a residential course but if they did and its anything like their distance learning course then I know where I would go (in hindsight and all that)...
Anyway for a residential ATPL ground school then I'm sure you can't do much better than Oxford ground school. I know a fair few people who have attended the Oxford ATPL Residential course (Modular) and they have all had happy experiences.