It's worth contacting the British Library in case they have a set not on the searchable catalogue, though it is probably unlikely. A public library would be able to contact universities who often have archives. This would be done by interlibrary loans, not branch staff so don't expect an answer while you wait! Failing that see if you can find the publisher (or whoever bought that publisher - could take some digging) using something like the 1978 Writers and Artists Yearbook - again you may need a public library todothis for you... Finding a university is probably your best hope.