Catalytic converter ?????

[Goldrover]

It seems as though i have a small hole some where in the converter-small amount of soot on the outside of the metal. Is this an unusual case and is it costly to repair/replace. I haven't the facilities to do this job myself also age isn't on my side for crawling under the car. Any advice on which way to go as to replace -mot coming up so they may be more costs.
Due to it being our daily driver and needed for hospital needs ,fast fitting companies are quick ,but there reputation is not always good.
Car is a diesel auto.
regards Dave