My colleagues who went to Oxford seemed to enjoy their course.
My advice for what it's worth. Finish your degree and then work for a year or two. Save your money and get some life experience. While studying and working do a lot more research on your school choice. You'll be about 23-25 years old and you'll still have plenty of time for the aviation career.
If you're still happy with Oxford, by all means go there.
However, I would not risk your Mother's house on your flying dream if you're not prepared to contribute financially upfront.