I think it looks beautiful in the photos OP. However, in the video you can see how small everything is. I think if it is just you and your partner most of the time, and one of the bedrooms for occassional guests, then it would probably still work ok. If you have children, or want to have children while you live there, then that would be a definite no from me. So I think that it's size is probably the main issue.
However, I would want and need further information on how that particular shared freehold works. Then how much maintenance fee each flat in the whole building have to contribute towards the maintenance.
I would them need a breakdown of everything the maintenance covers - does it include the buildings insurance? Does it include all the maintaining of the fixtures in the communal area, and what about the fabric of the whole building, and the fabric of the individual flats?
Does it include the really big payments, eg a New Roof, or a total rewire of the whole building, and/or your individual flats electrics? I have the same question for any plumbing probems, both for the whole building, the communal areas, your own flat, and any damage caused by any of the utilities that start in your flat, but then stretch to the other flats, and of course the other way around, where someone eles flat floods yours (I appreciate that that particular example would be rather unlikely as you are in the top floor flat!)
Is it in the rules that if someone has a major problem eg they get a massive crack open up in one of their outside walls, that that residence has to cover the whole of that repair themselves, or will the maintenance or insurance cover the whole cost, or does the householder have to pay a much larger contribution to an extra fund needed for the repair?
What happens if one of the flat's owner's become unemployed, and can no longer pay the "huge" maintenance fees, or if they have a major poblem in their flat that affects the fabric of the whole property? If they just cannot pay their bill/s, and end up having to sell the flat, but with the problems it has,
no-one wants to buy it?
Presumably if it is a problem that would affect the other flats, but the owner can't afford to repair it, you and the other freeholders would have to pay for the repair yourselves?
Does the building have extra insurance either within or without of the main maintenance contract, that will cover any emergency treatment or replacement, if the owner of the flat that is within the whole building, cannot pay some, or even any of that emergecy bill?
Also, if there is a main insurance of the whole building, and a different emergency insurance, are they both with the same insurance company? They really should (or even must) be with the same insurers, because otherwise insurers have been known to argue between themselves about which insurance the problem should come under - these sort of issues have been known to sometimes take months to resolve, and in a few cases, even years.
Meanwhile the problematic issue may get worse or even affect the building so much that the residents need to move out until their building is safe again, and actually does either of the insurances pay for the owners' to stay somewhere else in those sort of circumstances? I am sorry but I have run out of ideas at the moment, and it might be worth getting official advice on any issues raised in this thread, or thst you subsequently think about
Any of the points that I and other PP's have raised might be relevant to whatever property you eventually purchase, so I think that you should have a spreadsheet that covers all of the points you would want to ask any Vendor, their Solicitor, or probably in the first instance, their Estate Agents. Good luck OP, with whatever you decide, I am sure that whatever you end up purchasing OP will be lovely, and just right for you, your partner, and any present or future children you may have. 💐