There's a lot of guess work on this thread.
I can't tell you what you will get, no one can really, but I can tell you what I was advised.
Marriage of several years. I was a student and working part time.
Solicitor advised me I could claim limited spousal maintenance for a limited period of time - e.g. until the end of my course/so I could finish my course (so about 12 months). After that, I'd be expected to support myself without spousal maintenance.
I could claim child maintenance for the kids, of course. A private arrangement is preferred by the legal system but anything over CMS amounts is only enforceable for 12 months.
The simplest way to do all this was to ask him to pay half the joint mortgage still until the house was sold plus the child maintenance. My STBXH earned enough for that to be feasible and he agreed, thankfully, so it went through fine. If he'd disagreed, it could have gone very differently. (He'd been a financially and emotionally abusive arse but thankfully wanted to appear a 'good guy' to the rest of the world at this point).
That enabled me to get through the initial 'hump' period that came with separating and to a time when I could earn more.
I also separately confirmed I was entitled to Universal Credit but not the housing element if I stayed in the house. I claimed the UC I could get. I could have just coped with UC and my income plus child maintenance , if it have come to it but it would have been very, very tight. I did a lot of number crunching to ensure I could leave/have him leave and cope financially.
So much depends on what he earns, what you're asking for and why, and whether it all gets combative or not. Get advice on the specifics of your situation from a solicitor and talk to CAB about what UC you might get and then do some calculations.
Good luck!