Hello, I am a solicitor with 20 years experience. I will try to answer this for you.
I assume that you are outside any fixed term of the tenancy and are what is known as a periodic tenant?
Also have yo aid a deposit and if so when was it paid into a deposit guarantee scheme? This is relevant to whether the notice is valid.
Expiry of the notice period does not end the tenancy. A s21 notice is a notice on an intent to end a tenancy. Only a court can end the tenancy. Incinentilalt whose name is ***** ***** in on the landlord side. Are they the new landlord? If so ho do they claim to have become your landlord?
There is no prospect of a possession order being made within 3 weeks and even if it were you would almost certainly be given 3 weeks to leave by the judge.
You should write to the family explaining that you will be leaving in 3 weeks and that your tenancy has not been terminated by the notice. That, bearing in mind your intention to leave, any court proceedings would b a waste of time and you would show the judge your letter saying you would be leaving when the question of costs is dealt with.
I note that you say you have been there for 18 years. If the tenancy started before 1st March 1997 and you weren't served with the right notice at that time then you may in fact have quite a lot of security of tenure and the s 21 procedure may be invalid. I mention that, just in case.