Son and daughter-in-law have a lot of them fitted because they foster, but they're in the USA. I'll ask them which ones and see if they're available here - they work well through 3/8" plywood and would probably do fine through thicker wood, too. In any case you could always double up on the actuating magnet if necessary.
The only annoying thing with theirs is that the location of the lock isn't obvious from the outside, so you can spend a while fiddling about to get the exact spot to trip the catch. This is a nuisance if you are trying to get at the medicines box!
I think a sticky label or something would be helpful - they know the exact spot for each cupboard but we didn't.
E.