They collaborated on at least 3 and possible 4 or 5 albums if I remember correctly. I read (and just reconfirmed through a google search) that the collaboration on Chronicles of the Black Sword went so far as Moorcock providing narration between the songs during the road tour and mimes acting out the various parts (Elric, etc.). The Live Chronicles album supposedly includes all this that didn't make it into the studio album.
Oddly enough, I've never heard any of the songs from either the studio or live album of Chronicles
It's one of the few I couldn't get a cassette copy of. By the time I heard about and got into Hawkwind, you could only find albums in the Imports section of the record stores if you were very very lucky.
I haven't had any luck finding CDs of those albums either.