I've been able to get the Mann fuel filter for the 300 tdi here in Toronto through a VW parts supplier. Napa also sells a Wixx manufactured filter that works as well. I will post the part numbers tomorrow.
I haven't had any luck locating the air filter. Mann lists a part number on their website but I have been told that it isn't imported. I usually order a few at a time from Rovers North, Atlantic British, etc.
I happened to drive past you on St.Clair some time ago - I waved from a right-hand drive blue 110. Always nice to see other Rover's on the road.