I know, I know. I'm late to this by 8 years, but! I love it!
Have been doing a few sketches... (uploading on my tumblr) but here they are:
Amazing cast and just an amazing show! Bloody love it.
I used reference only for Guy at the bottom and a bit for Tamsin in the second one. None for Mac in the top one (which is why it looks nothing like him). I love drawing Tamsin Greig's face, she is just stunning!
I'll have to try drawing all the characters from the series though at some point!