Definately keep with the maths & physics, especially if you enjoy them and thats what you do your best.
General Uni advice- which I went on was down to Maturity. If i was mature enough i would have gone straight into training. You dont need a degree to be an airline pilot; u dont even need A-levels!
If you are gona be mature enough and employable age 19 then go for it. Otherwise take the 3 years for some development and get a degree in a subject that you enjoy and will do well at.
You just gotta weigh up the pro's and con's yourself- and see which does you best
Keep the dream alive!