Missing an LSE or UCL offer for PPE

Basically, I hold a firm offer for PPE at LSE, and my insurance is UCL, for the same course. My offer is A*AA with A* specifically in Mathematics, for both Unis. Before you chastise me for having two high offers, I did this with the intention that I would only go to UCL or LSE in the UK, I have back ups in USA. Now, the problem is, I am nearly done with exams, but I'm 100% sure I've lost my A* in Maths, as P3 went REALLY BADLY for me (I do CIE). My other 3 Maths papers may well be near 100%, but this one was horrific, largely due to terrible teaching and the exam being conducted poorly :/. In addition, I don't think I will get an A* in any of my other two subjects, Physics and History, so best case scenario, I'm looking at AAA (provided I haven't bombed Maths to a B). What chances will I still have at either? Is it worth mentioning that I did the SAT Subject Tests in Maths Level 2 (the higher level) and Physics and got 790/800 in both? Any advice?

If you had issues with the teaching then let the unis know asap. You'll need a teacher to back this up and explain the issues, as otherwise they will think you're making it up. The unis can then choose to be more lenient, and if you do brilliantly on all other modules they may accept you anyway.

You should have already told the unis about your SAT, so that is irrelevant. They will already know and will already take it into account.

Yeah the problem is I'm not sure how my school would react to what they might consider "accusations". Obviously if I can get them to take responsibility that would help my case.

As for the SAT, I actually haven't told them that in any way. Its not recognised by ucas, and I didn't mention it in my PS. Now did my referee I'm sure as she didn't even know I'd taken them. Do you think it still might be useful?