Just to clarify, do you mean the city of Gloucester itself, or the county as a whole so including the Forest of Dean ? (I ask as I don't know where you're posting from, and people often abbreviate the county name to just Gloucester).

Eitherway, my quick search of the net shows various tours of Gloucester looking at the various historical subjects including famous people such as Robert Raikes, but I've yet to see anything clearly "family-history" based.

I'm sure there are individuals, perhaps professional FH researchers, who would be happy to help create a tour around your individual needs, although I suspect this might be quite costly. I don't have a recent copy to hand, but the usual FH monthly magazines carry adverts for professional researchers and suchlike across the UK.

Hopefully other forum members can help further, but for now my suggestion would be to contact the following;

Gloucester Family History Society and Gloucester Archives, follow links on this page;
https://forest-of-dean.net/joomla/index.php/links/30-organisations

Gloucester Tourism Office
http://www.visitgloucester.co.uk/explore/tourist-information-centre

Gloster Guided Tours via Gloster Civic Trust
https://www.gloucestercivictrust.org/discover-gloucester/

Forest of Dean Tourism, eg
https://www.royalforestofdean.info/

and Nicola Wynn & colleagues at the Dean Heritage Centre
https://www.deanheritagecentre.com/learning/collections

Sorry couldn't be more specific, hopefully other forum users will help further, good luck.