Okay - well, there's clearly no point discussing this further with someone who just bleats 'case closed' and repeats themselves, but at least zsazsajuju isn't a landlord.
If anyone (tenant or landlord) is interested in reading up on the issue of landlord access, I'll post a list of useful links of landlord-oriented or neutral sources; these aren't tenants' rights blogs advising the best ways to outwit your landlord. These are sites trying to give landlords themselves the clearest advice about rights of access, especially where a landlord has legal obligations (to repair, gas safety cert etc) and might assume this gives them unproblematic right to access, subject to notice being served.
It's overwhelmingly agreed that this is not the case. Just because failure to gain entry places the landlord in potential legal difficulty (eg gas safety cert expired), it is not considered adequate grounds for them to commit a criminal act (gaining access against the tenant's wishes: trespass, or harassment).
Every site recognises the frustration of this for decent landlords with obstructive tenants, and suggests various legal measures, including injunctions, evictions and prosecution under the antisocial behaviour act.
But none of them say 'let yourself in'. I think the only positive thing anyone has to say about letting yourself in, against tenant's wishes, is that the tenant may not actually take legal action (especially if the tenant is denying access because they're up to something illegal themselves), or that the tenant's appalling/illegal behaviour may be considered a mitigating factor if it does come to court. But saying you might not get prosecuted is not the same as saying there's no grounds for prosecution.
And this is talking about really awful tenants who deny access for vital maintenance and inspections. If you've got an otherwise unproblematic tenant who's just, for example, asking you to reschedule an inspection so they can be present, it's absolutely mad to go against their wishes and let yourself in. Your liability is huge. The grey area is whether you can give them the impression that they have no choice, and get (reluctant) consent, or suggest their requests are making you angry and that their tenancy may not be renewed. Badly done, this could be construed as harassment.
Ultimately, it's up to the landlord to decide whether the inconvenience of doing maintenance or inspections on a more restricted schedule, in accordance to the tenant's wishes, is worse than the very real possibility of legal repercussions if they let themselves in against the tenant's wishes or make the tenant feel harassed. No: tenants who need their tenancy to be renewed may feel unable to complain. But tenants who don't need a renewal may actually be in a position to protect their rights, which is bad news for a landlord who's acted against all prevailing legal advice.