I did my own back when I was a little more active, cleaned the car thoroughly, clay barred and then coating applied. To do the whole car, wheels and glass took me 3 days and was hard going. Paint was an early start with decontamination and washes then application of ceramic layer.
I believe Motability didn’t allow a ceramic treatment on its cars, so I’d definitely check before buying anything.
If it’s just about having a clean car there are some decent hydrophobic options that will keep the car cleaner for a few weeks.
I'm Autistic, if I say something you find offensive, please let me know, I can guarantee it was unintentional.
I'll try to give my honest opinion but am always open to learning.
Mark