Nice to hear (and congratulations!).
IME landlording is an ultimate people business, and the product sits at the very core of tenants day to day lives. I.e. You have to manage it in a sensitive way. It is a strange dichotomy, it's your (probably very $$$) investment, but it's also someone else's home.
You can have a tenant tied in on a lease, but if their circumstances change and they have
to leave, there is little point getting clever and trying to stop them, or penalising them. I don't mean tenants acting in a discretionary way, I mean they have to
leave. This is just life, you can't go 'taxing' people, and you'd be fighting the wind if you did.
Then the best thing to do, is to seek to compromise. Agree dates. Give a reminder of exit terms (cleaning etc). Agree that access is permitted during notice period to 'view' the flat to potential others.
It can (and should) be a win-win. There is nil point trying to hold back a tenant who has to go. *On the flip-side* being amenable can come back and bite you, as I'm currently finding out with one property
where I tried to help the tenant (her friend/co-tenant left, she said she wanted to stay on her own until Spring), and I did my best to help her out, then out of the blue she gave notice to quit end Nov [nightmare time to give notice!!!]... so that's me in the hole for likely £6-10k, because I was 'sucker' enough to try and help... phhh ... **ck, I'm getting soft... [snort]
IME in landlording, you tend
to reap what you sow (refer previous paragraph for an exception) .. . barring the odd nutter/fruit-loop (one of which I have just this week... oh woopee) ... To quite an extent it comes down to understanding a landlord's motivations and concerns (which outside of SG usually involves wider matters than just money).