On one level, Op could just be asking about the worst case scenario to understand the timescales that could be involved. However, the tone of annoyance and sense she has of the tenants being unco-operative suggests a lack of understanding of notice periods and tenant rights which LLs really should understand and simply accept as the legal system they joined by becoming LLs, rather than feeling annoyed when tenants expect notice periods to mean exactly that.
It is absolutely the case that the tenants have a right to live in the property until their notice period expires and there should not be an expectation they leave sooner. They do not have to let people come into the property for curtain measuring or similar and to suggest that OP contacts them nearer the end of the notice period is both sensible and actually shows that they are helpful, rather than just saying no.
This response also suggests to me that they are likely to leave as the notice period expires. There is nothing to indicate anything else.
If however, they choose not to go, then eviction proceedings would need to start. Councils advise tenants who want housing from them to remain and wait for legal eviction proceedings to take their course, and that they will only house if people are made homeless. If they simply move out at the end of the tenancy the council will not do this. This is why some tenants do not move out as notice expires. There is nothing to suggest these tenants might be seeking council accommodation and so will remain. However, there is a possibility if it, so OP is right to be aware of it and yes, it can take months or longer than a year for tenants to then be legally evicted....and it is vital to go through the proper channels.
So, there are rules and procedures for everyone’s protection. Notice periods are exactly that. Tenants should not be expected to go sooner because it suits the owner or someone buying a property. There are procedures for a situation where tenants still don’t go. All of this can take months or over a year.....from the giving notice (6 months needed at moment, plus cannot be given until 2 months before fixed term) to possibly having to follow up with eviction proceedings.
BUT, Landlords know or should know this legal process and anyone looking to buy a tenanted property should know this process and the timescales. It’s no good moaning about it and saying it’s not right Landlords cannot get their properties right. You go into being a LL knowing the law and if you don’t, you’re a fool and are still bound by it.
So there is money to be made by being a LL, but also legal obligations and processes and these must be stuck to.
Op sounds cross about the timescales and critical of the tenants. They have done nothing wrong nor indicated they will do. It is worth being aware of worst case scenarios, but LLs also need to be aware of tenant rights and the system they as LLs are part of and not see wrong-doing where there is none. It is entirely their right to be there until notice expires. If they remain after (and no indication they will) well yes, that will be annoying, but again, there are processes to deal with it and you know as a LL that there is always a risk of that happen8ngand you just have to go through the process.