My understanding is that once the youngest child hits 18 then the house is sold or the resident parent buys out non resident parent.
My ex2b and I are going to mediation to agree what is fair, with guidance from trained mediator. Seems to be much cheaper way to do it than solicitors although we both need a solicitor to make our Separation Agreement legal at end of process.
I get legal aid for mediation as my income is low and unlike solicitors they do not take equity in house into consideration. My ex2b pays £700 this is for a package that includes agreements re children and finances, you don't have to do both. We have been told to expect 4 to 5 sessions but the £700 would cover a few extra if necessary.