So, my bike is back together again and it seems fine on first test. However, the speedo wasn't working - took wheel off again and two snapped lugs (apparently a common thing).
It's a nice simple job, if not just a little fiddly making sure that it stays in position whilst you try to get the axle bolt back on when refitting the wheel Shouldn't take long though, just make doubly sure that the lugs are sat properly
I've just bought the plastic one in advance. Because my front wheel is coming off for a tyre change, and the ceramic lugs have been superglued back on twice already....