Great shop. I used to work in Leamington and spent a fortune there. I would find new music on Pandora Radio (precursor to Spotify), then buy the CDs in Fopp.
As for bands I got into too late: Grateful Dead.
I assumed they were for hippie stoners, and never listened to them as nobody I knew had their records. Bought "American Beauty " over a decade ago and thought it was OK ish but didn't understand all the fuss.
After being on this forum for a while I found that @FinnDave played for The Grateful Dudes so I asked him what I should listen to. The answer is the live recordings, which the band actively encouraged and which are now available online or in many cases on CD as well. Totally different, completely mesmerising, I just love them.
I wish someone had introduced me to them when I was at Uni and could have seen them live.