Le Havre/UNESCO World Heritage Site

I can sympathize with your wanting a walking tour but once you get there it's all pretty obvious. This website will give you an idea of the area. Once you're there you'll see that architecturally, the idea is uniform construction and redevelopment of an entire area, not unlike ZAC plans in Paris

https://en.wikipedia.org/wiki/Le_Havre#/media/File:Plan_de_la_ville_du_Havre.png

Perhaps you can match that up with maps you already have. Do allow time for the one of a kind art museum. I don't recall any structures besides that being worthy of specific mention except for St-Joseph's Church. The architect Auguste Perret is also known for his design of the Théâtre des Champs-Élysées

There are many medical offices and businesses. There aren't any UNESCO World Heritage Sites in any language. You just walk around.
The backside of the Ecole Militaire - where there might be horses - is more interesting.

I couldn't find an English language tour anywhere online. I just did it myself by walking around and researching the major buildings in the city.

https://everything-everywhere.com/unesco-world-heritage-site-296-le-havre-the-city-rebuilt-by-auguste-perret/

I spent 3 days in Le Havre this summer to end my month-long Normandie extravaganza. In the ways of English-language marketing, you're not going to find much here. Not much too touristy. They do have a lovely art museum and the cathedral in the center of town - while phallic in shape on the outside - is extremely cool on the inside

I stayed at the Mercure Vieux Bassin. It was a fine spot and walking distance to most sites. The tramway didn't serve me much at all.

Strangely enough, I had one of the best chinese meals (outside of china) not far from the hotel. And also ate at a really cool restaurant (Les Enfants Sages) that has an excellent outdoor area to eat on.

There is also a nice little bus tour of the city for 10 euro.