Fixed term tenancy - notice of termination

[Confused2022]

I rent a property to students for 9 months every academic year.
This suits the students - they do not have to pay for the full 12 months.
To date I have just emailed them a month in advance of the 9 month period to agree a handover of keys and confirmation whether or not they will return the following year. Every year I issue a new fixed term contract for the applicable dates.
Should I be serving a notice of termination at the end of each tenancy and submit this to the RTB. If so what notice period would apply?
I cant see anything on this on the RTB website, the assumption seems to be that every one will want to stay longer than 9 months once they have right to security of tenure but this is not the case here.

 

[Greenbook]

I think it is fine to continue to do what you are doing unless you are worried that one of the students will want to stay on, a final year student who gets a job, for example. He will then have a six year tenancy and it may be awkward as he may not longer want to share with students.