Following the Tenant Fees Act 2019, landlords cannot ask tenants to have their properties professionally cleaned.
Tenants must return the property in the same conditions as when the let began, as per the inventory if one was provided at the start of the tenancy, minus general wear and tear.
If the property is not to the appropriate standard your landlord can attempt to cover costs by deducting these from your deposit but they definitely cannot contract with you to cover these expenses pre-emptively.