I visited in Oct 2019 with my son (12yr old), my brother in law and his 3 children (10-14).
We all enjoyed the tour - the Chelsea fan amongst the kids loved it!
We booked online in advance and then had travel problems in our group. They didn't bat an eyelid about moving us to a later slot so everyone to do it together which was good of them.
We had a quick look at the museum then went on the Classic tour. Our guide was fun and tried a few jokes along the way. You get to view the stadium from various points inside as well as see behind the scenes in the press room, dressing rooms and tunnel.
Overall, even though I'm not a Chelsea fan, I enjoyed it. I have also done the Man City tour too and would say that is better purely because there is more to it and you get to see the training facilities too (Chelsea's training facilities are in Cobham).
At the end you exit via the gift shop (as always!) ... bring your £££ if you want something!! (team shirt ~£60 and training top was £83!!).
Overall recommended if you have an interest!