@Rachel2677 You can look up proposals for STR in England on the government website . You'll need planning permission for commercial use. Does the Marina allow STR?
have a look at Airdna for likely demand
many areas suffering from oversaturated markets coupled with falling demand
you need to compare yourself against similar properties to understand demand - just because say two bed Georgian flats with a history of great reviews does well in Brighton - doesn't mean a new tiny home will 😁
well done for finding a tiny home in such a central location in a popular city - I know it's a dream for many who can't afford to live in such expensive cities.