I think the fact that you're worrying your Mitchell will be a self-insert means you're thoughtful enough that he won't be (but of course I haven't known you long, so unless there's a bit in the fic where he's worrying about how much time he's spending on YouTube watching clips of Charlie Brooker pretending to masturbate, I probably wouldn't notice anyway*). I certainly thought you wrote Mark wonderfully well, so I say go for it.
I've never actually gone looking for Peep Show fic before, although it's crossed my mind, and I've often felt surprised that I've not just hit more buzz about it, given all the slashiness you point out. The Mighty Boosh for instance seems to have a thriving fandom with plenty of fic.
the nurse looked exactly like the hypothetical child of Genevieve Cortese and Jensen Ackles AHAHAHAHAHA!
------ * but having said that, I realise I totally want fic where this happens.
I WANT TO LEARN TO PLAY THE UKULELE NOW
I've never actually gone looking for Peep Show fic before, although it's crossed my mind, and I've often felt surprised that I've not just hit more buzz about it, given all the slashiness you point out. The Mighty Boosh for instance seems to have a thriving fandom with plenty of fic.
the nurse looked exactly like the hypothetical child of Genevieve Cortese and Jensen Ackles
AHAHAHAHAHA!
------
* but having said that, I realise I totally want fic where this happens.