@Luv2chat2U 5.5 years.
I won’t lie, I posted on here when we made our offer on it and got a lot of replies that flats weren’t a good investment and the property market is dying and I wouldn’t make enough back; as any value my flat gained wouldn’t match what houses made… I was pretty scared I’d made a mistake!
But my flat has appreciated fine, and I’m now moving from a low mortgage (3x less than the rent I used to pay) to a medium mortgage; from a one bed flat to a three bed house with a loft conversion that we can get signed off if we want to. The flat value has gone up loads, it’s worth more than double now, and I’m moving to a house with no additional help from parents or anything.
I did look at lots of flats. This one is big and spacious, communal garden but outdoor space and lots of nearby parks, low services fees, low ground rent, nice neighbours. I’ve been really happy here. If I could make it work, I’d stay. I’ve dreamed about buying upstairs and putting stairs in for a long time 
Covid has reduced the gains made, like I said, we had an offers for £25k more in April last year but the buyer was furloughed and we didn’t want to list and sell again in the thick of lockdown.
It’s always a risk; and I’d buy somewhere that you’re happy rather than aiming for somewhere that’ll make money, but I do think there’s an odd attitude to flats here; perhaps because the average income of members here is a lot higher? But I’m glad I did it. It’s worked out really well for me.
I strongly debated keeping my flat and letting it out, it’d let for 4x the mortgage payment, but I’ve got enough on my plate at the minute without learning to be a landlord! And I’m selling to a lovely guy who is a FTB looking for his first house; and that’s quite sentimentally nice!
I can’t say it’ll work out for you, but I wouldn’t rule flats out overall. I’d be more concerned about being priced out completely than flats not appreciating, even post Covid.