polo burning oil smell

Hi there, I'm a first time vw owner, just bought a little polo for my girlfriend to learn to drive for a few hundred quid.

Its a 2001 1.0 mpi y reg and I have undertook a major service replacing the oil upon getting it home including the oil filter, spark plugs, ht leads and air filter

The car seems to be sweet, no overheating and the engine is smooth with good power delivery but now i have a problem. There is a very strong smell of burning oil coming from the engine but i did have a rather messy job getting the oil filter off having to hack away at it and put a screwdriver through it to get it off so i did get oil pretty much all over the part of the engine near filiter so it could just be this burning off causing the smell. But there is a film of oil accumulating on the bottom of the airbox and I'm not sure if this is separate problem or just the oil that is being burnt off from changing the filter. Also when i replaced the airbox on the car i couldnt find where one of the small pipes on the right hand side of the air box connects in the engine bay, so i just left it hanging lose. Just wondering if not connecting this small pipe could also be contributing to the oil smell.

Any help much appreciated, still on a learning curve when it comes to vws.