My DH's ex was in pretty much your position about 6 years ago I guess (before I met him). Her solicitor pushed for a life term of spousal maintenance, and his pushed for much less. They ended up with a 10 year term, which takes youngest DC to the age of 16, by which time she could be working full time. I can't really say how she feels about that, but from my DH's perspective it does become increasingly uncomfortable to have your finances mixed up with another household's. Decisions over changing job, retiring early, possible redundancy, etc all get mixed up with the implications for the other household. The logic of it though is that his increased earning potentail (relative to yours) is a result of decisions you made whilst married, so you deserve some compensation for as long as he goes on making higher earnings.
Why would you risk losing the house if the maintenancy stopped? Is there a mortgage on it? If so, I would very much push for a greater share of the assets if I was you, or a larger spousal maintenance for the first few years so that you can pay it off in a shorter time. Then the maintenance would finish only once you're mortgage free.
Spousal maintenance usually stops if you remarry (even if your new DH isn't earning anything), and can be reduced with a further court order if, say, your ex lost his job or something. Whereas whatever split of the assets you get is yours to keep regardless.
I think that spousal maintenance is normally awarded for X number of years, but with a reduction to a nominal amount (eg £1 a year) for the rest of your life, which would allow you to go back to court and apply for more if you still needed it after X years. That may be what your solicitor is pushing for, as it's unlikely your ex would agree to pay you a significant amount of money for the rest of his life. He'll presumably retire at some point.