I've owned loads of leasehold flats ( 4 in total) , my current flat is share of freehold though so I'm my own landlord who issues my own lease to myself. I've owned 2 houses freehold , both Victorian and don't see whats so great about it.
Bit dramatic to say all leases are shit! any leaseholders can get together if they've owned the lease long enough and buy it off the freeholder anyway as long as two thirds of the block agree.
Sounds like you got burnt on a shit lease. Most solicitors are woeful checking them , so as long as you fine tooth comb it or at the very least ensure someone does, you wont get burnt.
All flats have leases, so they are pretty hard to avoid! OP is buying a house, and will only have a lease to ensure the portion they don't own is retained by housing association , so they can charge rent.
It depends on the fine print of your lease, pretty easy to extend any lease, we got a flat with a low lease and as the seller owned the flat for over 2 years, we ensured they sold it with assign benefit of the notice, so we extended straight away, the freeholder couldn't refuse and if they try some outlandish valuation you just threaten tribunal and their solicitor will push the freeholder to cave in for a fair market price.
Some people prefer owning houses freehold over leasehold flats, I get that, both have pros and cons and its personal choice. I wouldn't say one was better than the other, you pay a service charge or you keep a fund to upkeep your house and pay buildings insurance.
OP is renting so as I said, better part buy than rent in any scenario.