You need an MSc to get CEng if you only have a BEng; MEng will jump straight there and has substantial management content - mostly in the final year. But, if you have a strong interest in aircraft design, BEng + the Cranfield MSc would be a good option, and possibly better than MEng.
75% in 1st year u/g maths won't be easy, and a lot of prior private study would be a good idea. This is the book most universities use:-
If you get in, a summer spent on your maths and physics would be well spent, because starting from only GCSE level, you'll find it very hard going at University. (People with A level maths will find it very hard going!)
P