Oohh Rusty, thank you for your belief in me!!
Actually, this is a steep learning curve - having never had a 126 before and the last time I really worked on cars was in the 90s!! I am an advice-sponge, so keep throwing it at me!
I'll see if I can pick up one of those brake hose spannery things tomorrow on my way to pick up the shoes and cylinders.
Interesting thing came up about the shoes and cylinders... I'm still umm-ing and ah-ing about the age of my vehicle (waiting to hear back from a nice bloke at Fiat on that one), but I'm putting it's date of manufacture around '77. The guy at the Motor Factors in Colchester said there were two types of shoes and cylinders on his system, so I needed to measure the brake drums and the bore of the cylinders... Thing is, it was raining, see?
So I opened up the manual (not-so-trusty Haynes!) and looked it up. Nearly went for the wrong ones, but I recently discovered I have rack and pinion steering, not the box, so had to head to the supplement section, post-August 1977, when they upgraded the steering as well as the rear brakes to a little larger.
I'll be picking up the shoes for drum diameter 185mm and rear cylinder bore of 19mm, front cyl bore 23.81mm. I REALLY hope this is the right pile of bits for my car!
The cylinders were SO cheap - like three quid each, I've decided to change them all round as well as the shoes. So, yeah, it's good the brakes did what they did at the test - forced me to do a bit of safety work, which hurts a LOT less than brakes failing at 50mph...
Otherwise, the nice guy called Bruce that did the MOT is a bit of a fan of 500s and 126s (hence I chose him!), obviously had a GOOD look round the car, and thinks I'm very lucky to find one in as good condition as mine - yes, it's a bit battered round the edges, but otherwise sound. The windscreen guy yesterday was also impressed at how little rust there was in those corners that see the worst rot around the windscreen. I was too when he pulled the screen off! He made sure he really sealed the new screen in well, too.
Anyway, thanks again!