URGENT Thumb turn cylinder lock on door question

[Tobythecat]

I'm moving to a new house (rented from family member) and he's put a new door in which features this type of lock; you lift the handle and turn the lock by hand to lock it from the inside, but you need a key to lock it/open it from the outside.

If I was to lock it from the inside, would somebody with a key be able to open it from the outside, even if it it locked on the inside?

Reason I ask is because this family member has poor boundaries and I made it quite clear to him that I dont want him just letting himself into my home when he feels like it. I said I would just put the key all the way through the lock so he wouldnt be able to open it from the outside, but he has gone and put this type of lock on the door and i'm wondering if he is doing this so he can let himself into my home?

The family member has made it quite clear by his deliberate actions that he has no intention of respecting boundaries or being a decent landlord. Is it worth the risk of moving in?

And I agree, I'd be avoiding this tenancy at all costs. If you do move in and assert your legal tenant's rights, he could give you notice the second your tenancy is up.

I’ve no advice to add re the lock, but I wouldn’t move into that flat on the grounds of what you’ve told me.

OP I know you said you are freezing in your current place of abode.

Make some heat socks.

Need clean unwanted sock, odds are fab for this.

Fill sock with rice or beans. Tie the end in a knot

Microwave in 30 second increments till sock is warm/ hottish.
they get quite warm and last well into a few hours at a time.

Never leave unattended. Never overheat. Overheating can lead to fire and fire will definitely warm you up but the down side is very down. No home nor personal possessions kind of down side.

Tell him your home insurance requires you to have a deadbolt lock.