Financial Settlement

[Sospanfach87]

My ex husband and I have (finally) come to an agreement about our house.
It's taken a while so I'm keen to get the ball rolling.
Basically, he has agreed that the house can be transferred into my name, I have a mortgage agreed so can take that over too.
But, I will pay him £100k in 5 years time. This means that the children can stay in the house until they leave primary school - It's suits us both.
I'm happy with this, but im worried about what happens if I can sell in 5 years. I won't be able to give him his money without selling the house. What if it just won't sell? Our last house took 2 years to sell!
Has anyone else done this? Is it possible to have something written into a legal agreement that says i have to give him the money once the house sells, as long as i put it on the market?

I know someone who did this, they had a document saying that once their youngest reached 18 and had finished school the house would be sold. I think there was a time clause in it, like 6 months.
They marketed it at a realistic price and as ‘no onward chain’ as they knew chains are what often stall house sales. She initially then rented while she then purchased something else.