Bluestone 42 Series 2 will be released on DVD on March 23rd and can be pre-ordered on Amazon.co.uk. You can also watch the whole series On Demand right now. The DVD will sell for £14 and is 1 disc. Unfortunately it is a Region 2 DVD so it can only be watched in the Europe.
Additionally, someone who was at a preview event for Series 3 revealed that the new episodes will begin airing on BBC Three on March 9th. This has NOT been confirmed by BBC, but is probably a good idea of when to expect the show.