If you have over £16k in capital (including a house you are NOT living in) then you won't be entitled to claim UC. Your own home is disregarded.
When you split from your husband your tax credits will end and you would have to claim UC.
Tax Credits only take into account income from capital, not the capital itself but you won't be able to stay on tax credits when you split up as this ends your joint claim and you can't make a new single claim for UC (unless you are in receipt of an Severe Disability Premium on an existing benefit but this would only apply on both you and your husband being disabled and already receiving an applicable benefit).
You can oddly stay living with your husband but having separated. You would need to be living separately in your home and not sharing things like meals or finances really. Things to demonstrate you have split. You could them claim UC as a single person (ending your tax credit claim).
Or if your income is low enough you may be able to claim UC jointly.
Please get a proper benefit check before doing this and consider that you will have to actively manage a UC claim which involves accessing your account every few days. You could a call Citizens Advice on 0800 144 8 444.
Claiming UC may also involved work related requirements such as job seeking, attending training courses, attending interviews at the job centre etc etc (obvs job centres are shut at the moment but thinking longer term). It's paid monthly and you have to wait 5 weeks for the first payment.
If you are self employed it's not great, and there can be issues if you are paid more frequently than monthly (although a recent court decision will hopefully mean this issue will not be one in due course). You also need to be careful what date you apply
Watch advance payments as they can put you into hardship for a year whilst deductions are made.
So be very careful before claiming and get some proper advice first.