Thanks for the good wishes and advice, chaps.
Me and my wallet are both very happy despite them charging £50 per test. She passed straight off (and I forgot to turn the fuelling down for the smoke test!)

Absorption co-efficient measured 1.38l/m of a 1.5l/m limit.
I got an advisory for the rear number plate, front droplink, a couple (OSR and NSF) of corroded but not seriously weakened hydraulic pipes and two partially flat rear spheres.
It
is the passenger side washer jet that's partially blocked, HDI! Oddly, I can stick the pin in the dribbling outlet all the way but the better flowing outlet will only take a few mm before the pin bends! Looks like replacement will be needed but I guess they'll be cheap enough - no air lines here I can use.