Just been to see a local air con specialist to find out where all my gas had gone, he put some test gas in and the leak was so big you could hear it coming out - no need for dye and UV specs

The leak is in the low pressure pipe from the evaporator block just before it dives down under the battery, it seems to go in one piece from the evaporator across the bulkhead, then comes forward past the service port and disappears under the airbox.

Long shot, but has anyone ever changed this? How big a deal is it? Becasue it is one lump I am worried about how much will need to be removed to get it out and the new one in.....