Help! Split with ex, 25 days isolation and no money

[Bubbleandboil]

Hi,
I split with my ex end of Oct.
He’s left without paying his half of the bills for the last month so I’m struggling to start with.
2days after this, dd nursery bubble had to self isolate, so I’ve taken the time off work unpaid to look after her as ex can’t/won’t.
I’m back at work for one day and ds’ school bubble has to isolate. So now I’m off with him as ex can’t/won’t.
I’ve submitted my 1st UC claim but I’m totally baffled by it all.
Will UC top up my loss of earnings automatically or do I need to apply for something else? Help, what do I do?
Ex hasn’t seen the kids since he left except via FaceTime. He wanted 50/50 care but due to his circumstances he can’t at the moment so we hadn’t agreed to any child matinence payment.
He says he’ll give me something at the end of this month but no idea how much??

Have you asked for an advance from UC?

No.
I started my claim days before any of this happened and before he told me he wasn’t giving me the money for his bills.
I would’ve been ok if the isolations hadn’t happened and I didn’t want to get an advance to have to pay it back.

Do you have family that can help you out?

Yes but I will have to pay them back.
I don’t want to be borrowing when I don’t even know if I will be able to pay anything back.
I just don’t know anything at the moment and I don’t like the uncertainty.

Uc tops up wages but won't replace them. You start off with a set amount of Uc dependent on your circumstances then your wages reduce that after a certain amount is disregarded ( depending whether you rent or have a mortgage).

Claim via CMS for child maintenance
Believe it is £20 to put in the claim