I would not waste my money going to Oxford it's a good school but they teach you so much and half of it's not examined and in the real world very little of the ATPL's is applied to flying.
I have been flying within the airlines for a while and can't recall anytime where I used what I was taught at ATPL level, the airlines will teach you what you need to know.
Bristol Groundschool in my opinion are among the best, cost effective and second to none in terms of quality of instruction and I have been to Oxford as well.
You will gain your licence regardless of what school you go to, you all have to sit and pass the same exams and flight tests otherwise if you could not gain a licence at a inexpensive school then they would not be offering to train pilots.