Is there a specific team he would be interested in?
I'm a Manchester United supporter and by chance my mum spotted an advert by the local branch of one of our supporters clubs one Xmas as they had tickets available - until recently went once a year with OH, the price included there and back coach travel and a ticket into the game, all well organised etc. Yes it was a long long day as we are not local but fine if you're able to sleep on the coach, and also just to get to go as general tickets are generally hard to come by
We've even sat on the Stretford end through them (and watched us get bashed by Tottenham 🙄)
Have also seen us play Liverpool a few times (serious fixture almost equivalent to a Derby through them - unfortunately the 5-0 thumping included)
If he'd like to go to Old Trafford look at the list of supporters clubs on the Manchester United website and pop an email/call to your local one
My one has the rules that you need to be a member of Manchester United and of the supporters club (about £40-50 in total)
I don't know if all their supporter's clubs do the ticket/coach option but certainly worth contacting
Sports breaks seems to be interesting I've looked on there for DH birthday for Liverpool but as I work in a school based role can only do school holidays so the fixtures are either out of my price range or underwhelming. Not sure on legitimacy but worth a look. First game we did was through Thomas Cook sport when they existed, it includes hotel which you can add extra nights for, which sports breaks does, but he'd need to travel to the ground himself so depends how affordable adding travel on top would be. We did a Manchester United game at Old Trafford and a Liverpool one at Anfield through them
If he's "natural" if you can afford it/able to get tickets, I'd go for one of the big clubs just to make it more memorable for him - Liverpool/Manchester United/Arsenal
Tottenham have a nice new stadium that I wouldn't mind visiting so could be another for the list.
Brighton are on the up and play good football so they are another option. Newcastle maybe?
If you get the chance to include an overnight stay for them, several of the bigger clubs have museums and you can do a tour of the stadium and view the museum. United's was great as it was lead by a person, who was so passionate and you got to sit in the manager's seat etc. Liverpool's was ok but until we got to the pitch a little more detached as it was listening to a tape thing it was much better the part we were with the guide
Edit - just seen he supports Manchester City didn't notice that at first, probably best not get him United tickets! 😏 try looking on their website to see if they have a supporters club , maybe email the club directly for some help/give them a ring. You'll almost certainly need to be a member to apply for tickets
If he can bare to sit in the away end and knows he wont celebrate you may be able to get tickets at one of the other grounds for when City play them but obviously relies on him not being able to celebrate so risky/less enjoyable and as a City supporter he will probably want to see their stadium