Turns out the above was well worth going for - the repair failed. In fact the ECU specialist had to let me down and admit defeat after it had already cost MORE than the entire kit from the breaker, so I bought the one from the link, it arrived yesterday, and I got the car started for the first time this morning - hooray!!!
I had got a source for an exhaust back-box, but I've been let down there too. The one at the breakers is a bit boring and standard, but I would like something a bit "fruitier", pretty quickly, and without spending a fortune. Can anyone help please?