Pension / equity split help

We are in the middle of trying to sort our financial agreement. Married 2& years, 3 daughters all know their twenties who live with me still. Ex husband lives with new partner and her children. I’m 47 and he is nearly 51. I stayed at home for 17 years bringing up the children and he has always been a high earner. I work full time now in education but only earn £16500k and he earns £80-100k but says want to leave job and take one with similar pay to mine as he is ‘mentally burnt out’.
Amicable split up to now but assets split is now causing strain.
Our assets are around £2million.
He has pension of £1.7million and mine are around £2000.
We have family home I live in worth £740000 and he moved out to a flat worth £300000 which he bought by remortgaging the family home. Mortgage left of £380k
He is offering to give me much more equity (80%) in order for me to buy a house around £500k. And he clearly already has somewhere to live.
But in return have to offset my pension amount which would leave me with £540k pension and him with £1.1million pension.
My worry is my future financial outlook. My salary is not likely to increase hugely, even with another job, so cannot increase by savings. I can’t afford, or would be able on that amount, to get a mortgage.
He has both options, although is obviously saying he want something non stressful and low paid now. But of course could choose to get a higher paid job once this is sorted and has the ability to get a mortgage.
And can also choose to keep the flat and sell pay off in 4 years when he can access a tax free amount of pension.
Is there anything that would say whether ( in fairness) a more equal split of the pension would be possible - even though clearly I am having to take much more of the equity to be able to buy a house right now for myself and the three children.
Thanks