So much to think about, isn't it 
Firstly, it has to be a yes to seeing all the paperwork!
Estate agent valuation less 10% - well, yes it should be reduced from EA because they'll over-value them. But is 10% right? I don't know. But have you looked up similar properties on right move and zoopla to see what they are on for - and better still, recently sold for? He might be being honestly, or he might not. What he definitely will do is naturally lean towards the better end of a deal for him, even if it's vaguely fair overall.
So that's the first thing - get the paperwork, and do your own research.
Then this question of him keeping them or you taking them? I just don't see how you could take them. I just don't see a £15K salary getting you through an affordability check to take on TWO mortgages, even with proven rental income. So check what he is suggesting is even possible! Are you on the mortgages now? Do not do ANYTHING informal. If you take the equity and income as yours but his name is still on them - find out from a solicitor if you can make that legally binding. Unless you fancy paying the mortgages for not a lot of rent for ten years then him saying "time to sell up, that equity is half mine!"
Never ever trust someone on something like this!
On the pension - it's exactly this sort of thing you need a solicitor for. And why you need to see his full assets. Are you sure there is only one pension, for example? This one in payment now... seems early as you're only 45. Is he older than you, or is it military / police / some old and very specific NHS so earlier payment? If he ever had another job, chances are there is another pension.
You need to know exactly what signing over the pension entails, if he can do it, how much it will be.
As to your share: there are no absolute rules, you negotiate. And that's where a solicitor will help you with what is reasonable. What about your pensions? But it's quite normal for a woman financially disadvantaged from child rearing to request and get more than 50% of assets.
What's the detail behind the debt? Whose name is it in? Even if in his, it is part of the marital total so yes, your share could be reduced to reflect it. But if it's in your name he can't actually GIVE the debt to you.
No bailiff is going to chase you!
What was it spend on? If it was families holidays - yeah, accept it. If it was in a flashy car that you didn't want and never got to drive and he still has... argue against taking a share.
Yes, he can ask for his £20K paid this year to be considered. But I would argue that at least some of that he should have been paying anyway. Even though he doesn't owe maintenance for grown children, you have housed his kids. And fed them.
Look, I know I sound like he's an arsehole out to stiff you!
He may not be.
But information is your friend.
Do not be rushed, get all the information.
I'm
about 2 properties having only £30K equity between them. OK, buy in early 2008 on a 100% BTL mortgage and it's easily possible. But it's low enough that I'd want to do my own research.