I entered directly from school without going to uni.
It has paid big dividends along the way. I have always been quite young for my grade, and don't forget, you are paid for training with NATS.
I also have 3 children at university, they are not particularly interested in ATC, and it costs a fortune. At least 8000 pounds per year each (one is 12000!).
What will you do with a geography degree? A degree does not guarantee a job in this economic climate.
My advice is to apply. What have you got to lose? You can always get into university, in fact the older you are the easier it becomes. There is an age limit for NATS.
If, down the line, you decide you still want to study for a degree there is always the Open University. You would not be the first NATS employee to obtain a degree from there.
Good luck with whatever you decide.
flowman