Bristol Ground School are fantastic but be honest with yourself with regards to your capability to study on your own! I've found it hard enough to get my PPL exams done let alone the ATPLS! I'm the sort of person who needs to go away and attend lessons and be taught by a person with people around me in the same boat. My bedroom is far too comfortable for me to study in which is why I've decided not to opt for BGS and go to London Met.
Good Luck!
S88