The landlord must not put the deposit in an escrow account it must be in a government approved scheme otherwise you have a claim for compensation of up to 3 times the deposit plus the return of the deposit. Further, he has to give you the details of that scheme within 30 days of you giving him the deposit otherwise once again, you have a claim.
He cannot give you notice to quit unless he has protected the deposit although if the tenancy has come to the end of its term and rolled over into a periodic tenancy he does not have to have a reason.
Section 21 notice is given to vacate at the end of the term or section 8 notice in respect of arrears or other breach of tenancy. That can be given at any time.
Section 21 must not be given within the first 4 months of the tenancy and currently, the notice periods have just reduced although they are higher than they were before the pandemic.
Any notice must be in the statutory format in writing.
The notice period originally was 2 months under section 21 and it could be as low as 2 weeks under section 8 but it changed to 3 months on 25 March last year and to 6 months on the 31st of June last year.
From , 1 June 2021, those notice periods are now generally 4 months.
However certain notice periods are shorter such as rent arrears but there have to be far more rent arrears now than there were before. It used to be 2 months, notes 6 months. So it appears to be more favourable to the landlord but in actual fact it isn’t.
The government have produced this webpage on exactly this subject:
whilst it’s unfortunate that you have built your business, the landlord doesn’t have to let you stay beyond the contractual period of the tenancy