Has anyone done M4?

Summary: Has anyone done M4? How much of it depends on M3? Can you revise the content in 3 weeks along with other exams?

So I'm in Year 13 and I'm doing MEI OCR, and I need an A* in Further Maths - this means getting an average of 90 UMS in my 3 A2 Further Maths modules.

For Maths and FM, I'm currently taking: C3, C4, M2, S2, FP2 and Numerical Methods (which is AS so doesn't count towards A*). My exam board is OCR MEI.

I've studied barely any M4 because obviously I wasn't intending on taking it. But I had my M2 exam a few weeks ago and it didn't go well - I'd say I maybe got 80 UMS but obviously I can't tell - that's just an estimate. I can't see myself getting an average of 95 UMS in S2 and FP2. I could probably get an average of 90 if neither paper was horrible.

The M4 exam is in 3 weeks. Has anyone done M4? How hard is it? Is there some other course of action would be better? Should I enter myself for M4 now and take a lot of the next 2 weeks to revise it? S3 would also be an option, and I made a similar post about this a few days ago - the reason M4 might be better is that I'd have about 10 days longer to revise for it (even though it would be harder).

Any advice or information would be much appreciated.

I haven't done M3, which I realise could be an issue, though the specification says you don't have to have done M3 to do M4. Does anyone know how much the content of M4 depends on M3?