Engineering advice needed!

Hi everyone.
My question is with regards to doing aeronautical engineering at Imperial, bristol, southampton, bath or mechanical at UCL. I am in year 12 (two exams left!) and need to start thinking about uni. The grades are pretty similar but the highest grades i would need is for Imperial which is the A* A* A with A* in maths and physics and third subject strongly advised as further maths. I currently do maths, further maths, physics and chemistry at as. At the minute I am pretty sure an A* is a very high chance in physics and chemistry and with maths if i work hard enough next year and based on these exams so far. My question is regarding the fourth subject further maths.

See (worst comes to worst), the A* is required in maths which i can do i hope and an a* in physics but the third subject is advised as a further maths and i messed up my s1 exam pretty badly meaning i would be grateful with a d (40/100). Just a bad day really. But it will drag my as grade down in further maths to a probable b or c. I am resitting but will they know that and accept that or will they look at the other three even though further maths is strongly encouraged? Any help would be muchly appreciated since i have been worrying about it for ages. I apologise for the confusing writing, english isnt my strongest subject. Thank you so much.