Whatever you do, don’t take a gap year. Judging by your attitude to uni right now, after a gap year you most probably won’t even want to go back.
As for retaking or going to another university, could you have worked considerably harder? How close from passing were you? Would you ever be able to attain a 1st or a 2:1 at imperial? Consider all these things. Honestly there’s no point getting a degree if you’re going to get a third, so maybe switching might be ideal, with 4 A*’s you could pretty much go wherever you want, maybe one of the less prestigious Russel Groups?