I was in the same boat as you, in fact, I was booked into Oxford then as soon as I went down to Bournemouth to look at Cabair, I changed my mind.
Cabair has better pass rates, and the instructors are top quality, I'm not knocking Oxford but you are paying for the name.
At the end of the day if you put the hard work in, it really doesn't matter if you go to Oxford or Cabair or Bristol - but I would definitely recommend Cabair Bournemouth for the ATPL study.