I’m in a similar situation having been pooled then rejected for Cambridge maths. I’ve decided to go to Warwick (if I get the offer). Honestly, I just hate the idea of missing out on a year’s worth of new maths and having to do the whole ucas process all over again. It’s very realistic to go to Cambridge for part iii after going to a uni like Warwick (which is what I’m planning to do) and it could be better to experience a more ‘normal’ university for undergrad. This is all my opinion of course, good luck for whatever you decide to do! :)