Well the starting point is 50/50 - so £135,000 each if the house is sold (less fees), £5,000 each from your pension, £100,000 each from his pension and £30,000 each from savings. Plus monthly maintenance for the children.
So you could each walk away with around £270,000. OR as you have suggested, you keep the house, and he keeps his pension and savings.
As you have a child with additional needs to which you are the primary carer, and you have been unable to amass the wealth of your STBXH due to caring responsibilities, you have some arguments there to move away from the 50/50 starting point, and possibly ask for some of the savings/pension too.
I suppose it depends on whether you want to just get it done on ok terms, or if you want to fight for all you can get!
Given what you've said about the house being adapted for your child's needs, I don't think a mesher order would work. The child's best interests are always a primary consideration.