The series has never been released commercially on video or DVD and to the best of my knowledge the BBC has no plans to release it.

My copy appears to be from a New Zealand screening. Originally it was on video and the sound was problematic, but thanks to a friend in Canada the sound is fixed and it has been transferred to a "region free" DVD. The tapes have been transferred to DVD and they reproduce remarkably well (thankfully - since it is probably the only way anyone will get to see the series again.)

The DVD is 'region free' so it will play anywhere in the world.

As for any prospect of the BBC releasing it commercially ...