burning smell

Hello everyone, first post here so I apologise if this is in the wrong section and thanks for any help in advance! My car is a 2005 Manual Petrol A150 A-Class W169. After starting the car around 20 minutes later I get an electrical burning smell coming from under the car near the drivers seat...

I've noticed a burning smell coming from my car after having been driven. I think it may be from the catalytic converter which appears to have some residue/gunk on it. The coolant level seems to have dropped slightly, so I'm thinking the coolant is leaking from somewhere and running down to the...