The Green Green Grass DVDs

Does the series three DVD contain the 40-minute 2007 special?

Yes.

https://www.comedy.co.uk/tv/the_green_green_grass/buy/

See Amazon product listing
[p=http://www.play.com/DVD/DVD/-/26/55/-/9229263/The-Green-Green-Grass-Series-3/Product.html]
[h=951763]

Might get that then. Missed the special way back in 2007. Looking forward to seeing it.