There’s 15 GBG pubs of current or recent editions in Pompey though
I am very reliably informed that near the ground for your real ale types (i.e. me and most of London Alty) is slim pickings. Southsea around the Common is apparently an excellent little circuit. Gunwharf Quays around the ferry terminal & your famed Fullers pub the Still & West for Saturday night out on the razzle. Hope the players get to have a bit of craic after the game too whatever the result-they all deserve it for an outstanding cup run.
Not too far away in the grid of streets between Fratton Stn and the Albert Rd in Southsea there are some very good backstreet pubs with decent ale selections and walkable from the ground. The Lawrence is excellent as is the Sir Loin of Beef which is a bit further away. Various others in the same area worth a visit. Sadly the once amazing Leopold is now a shadow of its former self. Pubs in Milton and the spoons in Fratton will be rammed with Pompey and are not generally a good idea for visiting fans. Gunwharf isn't great for pubs, just the Customs House, Fullers and expensive and a long way from Fratton Park. Good for restaurants though. A decent spoons next to Portsmouth and Southsea Stn but again a fair way off. Southsea Common ok but probably a cab ride.