https://www.lease-advice.org/ is a good website for information about leasehold properties.
The studio does come with a share of freehold too, so hopefully a long lease. Ordinarily when the freehold of the property comes under the control of the leaseholders, the leases are extended to 999 years and the ground rent reduces to a "peppercorn", so it is unusual to see that £50 is still paid each year on the studio, even with a share of freehold.
For whichever flat you're looking at, if you're serious about putting an offer in, I'd ask to see the most recent service charge accounts. That will show you how much money is held in reserves for any major repairs, such as the roof if it were to start leaking. This would all be needed during the conveyancing process anyway, so the vendor will need this information to hand at some point anyway.
Even though the studio is a ground floor flat, you'd still be responsible for 50% of roof repairs, for example, unless there are sufficient reserves to cover it.
Given it doesn't look like there are many communal parts to the flats in the property, £1,100 does seem quite high. Much of it is likely the buildings insurance for the property, but it's worth looking at where else the money is going.
And yes, extending a lease when you have a share of the property is much easier as you're effectively partly granting permission to yourself to extend the lease.
The cost of the lease extension goes into the freeholder accounts (normally a limited company), but this is then taxable in that company. The net "profit" from issuing a lease extension is then available for the freehold company to pay a dividend to the shareholders, so you might get some of it back that way.