Hannah,
I did Mechanical Engineering at University. So, I was thinking something along the engineering lines, as opposed to Sports Science or a degree in Underwater Knife fighting at Hollyoaks College...
Anything engineering based stands you in good stead. Not critical, but it gives you options to fall back on if you cannot get a flying job straight out away. Also, if you're working you have the means to fund your flying training. I was not a natural mathematician at school, but I worked hard and became one. Don't write yourself off. I often found that the subjects I couldn't do initially were the ones I ended up being good at, because of the extra time I had to put into them. Just my experience...
My reference to Sleap Aerodrome was to Joe. Incidentally, a good cafeteria ususally ticks the box on my aerodrome hit list!
Have a look into the forces, you'd be surprised what you can do. A bit of research doesn't hurt. Incidentally, the Army doesn't just 'kill people'... It defends this nation and it's interests from people who want to attack our way of life...
Good luck!