First of all, unless you were offered an unconditional for an Aero-Eng degree (or similar) at a top ten uni, or you can get such an offer through Clearing (which is apparently a buyers' market at the moment), I'd consider other options.
I know someone who many years ago wanted to get into LSE, back then it was the top university for anything economics-related. However, their A-Level grades simply weren't good enough, so they re-sat them and got in on the second go. A rather successful career in the City followed. If your results include Mathematics or Physics at a D grade, I'd re-sit. This is especially true if you have the cash or loan options available to go on one of the self-funded airline schemes. I think, historically, the BA FPP was BBC at A-Level minimum, Virgin Atlantic was GCSEs, Aer Lingus was Irish Leaving Cert (can't remember the minimum grade requirements) for their airline-funded programme.
If you don't have the financial options for an airline programme, I'd get a trade and do modular. Plenty of vocational apprenticeships out there which pay good money. Your goal for modular has to be maximum cash (I'd say £60-70k, though it can be done for less) in the shortest period of time.