If you put Lufbra down as your firm choice for Aero they are quite flexible (or they were when I applied)
For example, if you apply for the MEng (AAB) and only get the BEng grades (BBB/ABC), they'll take you on the BEng course, if there's space.
And, vice versa if you applied for the BEng and get AAB or higher, they'll let you go onto the MEng at the start.
And, I believe, if you totally screw up, they even offer you spare places on the other engineering degrees, depending on how badly you screwed up.
And finally, if you go onto the BEng aero course and get an average mark of 55% or more in your second year exams (1st year doesn't count to anything!), you get the option of going up into the MEng degree. Likewise, if you're on the MEng and get less than 55% in the second year, you may find yourself staying at Lufbra for less time than you initially thought.....