You can claim the childcare element for the costs of Care Inspectorate registered childcare you pay for, but you can only claim for the amounts you actually pay out. You cannot claim for costs covered by any government grants, including childcare vouchers, or education funded grant.
For further advice about childcare cost support access - https://www.gov.uk/help-with-childcare-costs
Please be aware that the legitimacy of Universal Credit claims is checked by the Inland Revenue. In addition, the nursery has a duty to report any known fraudulent claims to the Inland Revenue, this includes non payment of fees.