Can remember watching this series as a kid. Was presented by Julian Pettifer and first broadcast in 1978 or '79 I think. This was about the time that home video was emerging with VHS battling it out with Betamax and I don't think that commercial re-sale of TV series was seriously explored by the Beeb until years later so you may be out of luck. You might have to hope for a re-run on one of the satellite documentary channels.