Being housebound, my beer and facts-fetching wallah has misinformed me and so I you. It’s called the Beer Emporium, underground at 15 King Street, and rejoices as a bar, restaurant, and bottle shop. Yes, it sells many excellent Belgian beers. No, it’s not exclusively Belgian. I’m not certain when they started but fairly recently, I’m sure a researcher of your calibre can find out. They won A Big Prize in 2014.
There is a Little Belgian Beer Emporium in Worthing, at 41 Lyndhurst Road, with a stock of 60 beers. Who knows? They might sell hand bags, Lady Bracknell.