The Swan is great pre-match especially if the weather is nice to sit/stand outside with a drink. However I'd suggest Dick's for your needs, especially if you're prepared to get there 2+ hours before kick off.
https://www.stagecoachbus.com/news/south-east/2024/april/stagecoach-announces-brand-new-bus-service-linking-eastbourne-and-brighton
"From Monday 13 May Stagecoach will launch a new bus route, the 701, running between Eastbourne and Brighton via Seaford and Newhaven.
The hourly service, which...