Extra Pure/FPT Materials

Try this: https://amsp.org.uk/resource/4b42a0ae-0857-49c3-5f88-08dabcb692fe/
OCR MEI is one of the less popular boards for FM and so it has a distinct lack of resources available. This and PMT are probably the best you will find.

does it have anything on extra pure? it seems like everything but it is on there

As promised, looked around and given it some thought. As there were no dedicated resources, I had to compare specifications.
Extra pure covers recurrence relations, groups, matrices and multivariable calculus.
OCR A has a module called “additional pure”, which covers a lot of the material in extra pure plus other topics - it only appears to miss the matrices part of extra pure.
As such, you should be able to use OCR A materials to teach yourself the recurrence relations, groups and multivariable calculus (Surfaces and Partial differentiation). You can either ignore the number theory and further vectors topics or give them a look if you think they’d be helpful.
This has a nice explanation of groups at the end - everything else seems to mostly be material you will have covered in the core pure: https://www.mathshelper.co.uk/alevel_docs/OCR%20Further%20Additional%20Pure%20Revision%20Sheet.pdf
This should also be quite insightful: https://pmt.physicsandmathstutor.com/download/Maths/A-level/Further/Additional-Pure/OCR-A/Additional%20Pure%20A-level%20Formula%20Sheet.pdf
As for matrices, I believe you only need to be aware of eigenvectors/eigenvalues (and their applications to transformations), diagonalisation and Cayley-Hamilton theorem. Eigenvectors/eigenvalues and diagonalisation are on the AQA syllabus and so use of AQA resources may be a sensible place to start. https://pmt.physicsandmathstutor.com/download/Maths/A-level/Further/Core-Pure/AQA/Cheat-Sheets/Matrices%20IV.pdf
The applications of eigenvectors and eigenvalues and C-H theorem seem to be the only things exclusive to OCR B extra pure. I reckon you’ll need to just look up what the heck these things are and hope you can find an accessible explanation that doesn’t give these topics a gratuitously advanced treatment
Correction: Edexcel FP2 is even better for matrices and covers C-H theorem: https://pmt.physicsandmathstutor.com/download/Maths/A-level/Further/Additional-Pure/Edexcel/FP2/Cheat-Sheets/Ch.5%20Matrix%20Algebra.pdf