I've just done my first mitre cut with a borrowed router and jig. Turned
out quite nicely. However, when I was cutting the worktop, any time the
bit was near the moisture barrier at the bottom (so on the last pass of
my female cut and all the way through my male cut) it looked like the
whole affair was about to catch fire - lots of smoke coming off.

Is this normal?? The worktop is a B&Q Ebony black gloss.

Ben