You're not trapped. Your situation is not difficult to resolve, and when the MH exceeds the needs of the resident party; it will be ordered to be sold. So the mortgage you pay for four bedrooms, will not exist.
Two other things. She may get a larger slice of equity if she trades off claiming against your Pension. She will soon need a Pension, so she may retain a Lump Sum to afford a one bed home (flat?) and a sum to invest.
She could also retain some spousal support to meet her needs; but since she's re-training at college - you have a strong argument that she can soon gain work. Judges don't make allowence for work-shy folk; regardless of how 'clever' you believe she is. It serves your case well that she is at college.
She is not that clever if she does not yet realise two basic things:
1: The if she gets legal aid she will have to agree to mediation. (Unless you are violent or controlling and this puts her at risk)
2:
Legal Aid is a LOAN. The
LOAN will be repaid once her settlement is awarded. I believe there's an 8% interest on it, someone feel free to correct me if I'm wrong!?
So if she clocks up £30,000+ on going to a final hearing, she'll realise she's got a big debt to repay.
Where she is clever: is making you believe the situation is not worth resolving, and using stalling tactics, bullying tactics, and using the services of a solicitor to intimidate you away from a
fair settlement.
SHE IS NOT GOING TO RETAIN A FOUR BEDROOM HOUSE. Unless there are tons of other assets that can be retained by you.
If I were you - I'd move back in. Force her hand in divorce! (Illegal in marriage - but it works on divorce!!!!)