If he hasn’t changed the locks, then I would do that. The reality is that unless you become a nuisance there is very little that he can do about it on a single occasion.
I have come across this before in rented properties and usually it’s because the tenant dries washing on the radiators without opening windows.
What also happens with this kind of tenant is that they don’t allow access for repairs and then they complain about lack of repair so make sure you’ve got dates times et cetera every time that you were wrong and try to arrange it.
Let’s face it they have to come home sometime so they can’t be too busy to let you in for an hour or half an hour or even 10 minutes to have a look. So like you I don’t accept what they say.
You may find the other reason that they don’t want you in is that the property is a mess.
The alternative of course is to threaten a court application and legal costs for a court injunction to compel them to allow you access.
Thank you for letting me assist you with your legal question. I am glad that I was able to help.
I am not certain whether that answers the question for you or not, but I am happy to answer any specific points arising from this.
It will be my pleasure to help you again either further with this or any future questions you have
Kind regards
Stuart