Gap between tenant contract expiry and check out report - liability concerns

Tenancy Types and Management

Tenants contract is due to end on Sunday 28th Feb 2021. The usual requirements are in place for them to return the flat is a good condition, with cleaners and repairs being undertaken.

A check out report can either happen on the Saturday 27th Feb or Monday 1st March.

The tenants can not do Saturday as their new flat isn't ready and they wont have moved out. That means I feel I have to be flexible and do the check out on Monday.

I wanted to find out if there are any legal aspects I need to be aware of before agreeing to this Monday check out. These are not limited to, but include the tenants having keys post end of contract and I am not covered if anything goes wrong. However if I collect keys on the Sunday and provide to the check out clerk on Monday, then tenants in theory could challenge any of the report and say it was done after they moved out.

I want to be flexible but don't want to be left short on these fronts, or any others I haven't included, if the worst did happen.

Is there any easy solution and what are the options available? i.e. Contract extension for 1 day either formal (assignment to lease?) or implied via email confirmation and payment for 1 day? Or could I ask the tenants to agree that the condition of the flat is not debatable if the check out happens on the Monday?

Thanks for your help
Alex