The limit for one child is £646.35 per month.
How much help you get towards childcare depends on your income.
You get £594.04 as a couple
£235.83 for your child
Possibly an amount for your rent?
Then £476.85 for your nursery fees (85% of your fees).
The work allowance is £292 or £512 if you don't get help with housing costs.
So, say you get £1306.72 (no housing help). Your work allowance is £512. After that, every £1 gets £0.63 deducted.
If, between you, you got £1267.04 + £566.80 = £1833.84 (minimum wage full time + minimum wage 15 hours).
You get The first £512 free, then £1321.84 x 0.63 = £832.76 deducted from your claim.
So you'd end up with £1306.76-832.76= £470 Universal Credit. So you wouldn't 'see' any of the childcare money, even though it was in your claim.
If you can give some numbers, we might be able to help you work it out.