This is the first seven albums and you can't go far wrong with any of them. I would also add The Space Ritual live album, Sonic Attack (not popular with critics) and Rober Calvert's Captain Lockheed.
1970 Hawkwind
1971 In Search of Space
1972 Doremi Fasol Latido
1974 Hall of the Mountain Grill
1975 Warrior on the Edge of Time
1976 Astounding Sounds, Amazing Music
1977 Quark, Strangeness and Charm