Hello Steve, Have your shop pressure test the cooling system straightaway as it is quite impossible for me to do so from here, I suspect the cooling system with all of the plastic, has sprung another leak, possibly from the same thing that had the expansion tank go, age and thermal expansion/contraction. Sound reasonable mate?

Also send the last 7 of the vin and the part numbers of all the parts replaced, I have seen the E46 cars leak when the manual and automatic cooling system parts have been co-mingled, which is a no-no!