Suggest you start with Irish Tour as it covers pretty much what Rory was about and then explore from there. Btw, his drummer Rod de'Ath was a great foil for him (
http://en.wikipedia.org/wiki/Rod_de'Ath), and there are many clips on YouTube that span the next 5 or so years, which are worth a look/listen. Good call on Alvin Lee. Others you might want to take a listen to; Kim Simmonds (from middle-period Savoy Brown, though the real talent on these records was vocalist Chris Youlden), Peter Haycock (Climax Chicago Blues Band), and Jim McCarty, who is not too well know, but played some smoking guitar on the three Cactus albums (Cactus, One Way... Or Another, Restrictions) and before that with Mitch Ryder & the Detroit Wheels. I'd also recommend listening to Rod Price on the early Foghat albums with Chateau Lafite 59 Boogie being a great example of his slide playing. Finally, and even if you can't stand Lou Reed, everyone needs to listen to Rock and Roll Animal. The dual guitars of Steve Hunter and Dick Wagner are still amazing. Ok, one more - - Robin Trower, Bride Of Sighs. Of course there are many others like Steve Marriott, Paul Kossoff, and Mick Ralphs. I could probably go on.