Believe I've over paid into a SIPP.

DRS1

There will be people on here who know a lot more about extracting yourself from SJP than I do.

One thing to say (although you probably know this already) is that for both the pension and the ISAs you are going to need a receiving pension/ISA set up and that receiving pension/ISA should be the one to instigate the transfer.  Sometimes providers give incentives to transfer a pension or ISA to them and it may be worth checking if any are doing that now.  I may seem to be going on about AJBell (no idea why as I have never used them) but they have something here Transfer In Offer | AJ Bell

The question of whether someone is prepared to "deal" with you if your pension pot is not huge is probably more of a financial adviser/IFA question.  Most of the DIY platforms would take small pensions (HL even help you create a small pension if that is at all helpful - but I doubt that will be relevant to you).  I am not sure how easy it will be to find a new adviser if that is what you want.  That is partly why I suggested you go gently with the FA in case you got on with her and wanted to stay with her.  Plenty of people on here DIY though it can be daunting and with under 10 years to go you obviously don't want to be making any rash decisions.