nanasam, you still have series 3 to watch as well...
I've just been emptying my cupboards to see if the DC ever gave me series 1 on dvd, but no luck - I have found several unwatched series of Mad Men, The Tudors and Rev, but they're not calling out to me in the same way!
Thank goodness it's not too realistic - it's a drama, not Slow TV! Police officers do socialise, meet up and yes, argue with each other off the job, like any other work colleagues, so I'm prepared to go along with the scene at the forensic bloke's flat. She knew the address, so they must know each other pretty well.
Can't wait for episode 2!