Peter Kay is a great comedy actor and a natural born stand-up comedian. But sitcom writing is not really his strong point. Phoenix Nights and especially Max & Paddy don't really bear repeat watching in the way that The Office of Extras do. Anyway...
It seemed to me like Gervais was having a pop at just about every British comedian actually! Appearing on comedy panel shows, releasing a single, making too many series, relying on catchphrases, popping up on frothy BBC1 dramas, making a show of doing work for charity.
If he was having a go at anyone it was David Walliams!
Besides, I'm pretty sure Ricky Gervais once had a boxing match with Grant Bovey for charity and recorded Free Love On The Free Love Freeway as a single (and rewrote The Office to make the Xmas special accessible to a BBC1 audience) so he's not sparing himself either!