It seems whatever method I use I sometimes damage the wire and have to hope I have enough cable to have a 2nd try.
Is there a method that works 100% of the time for someone that is not doing it every day?
A possible duplicate has been pointed out, however it talks about 12/10 guage "Romex" rather then the normal 2.5mm twin and earth we have in the UK.
There are tools which do the job for you. They will probably take a little adjustment when first used, but then they're fine. They are literally the easiest way to consistently strip mains cable.
Many years ago my father had a hand-held tool explicitly for stripping Australian 240V household wiring cable. It had two clamps, two blades and a two-part action. The first clamped the cable and made the cuts, the second separated the clamps, neatly stripping the end off the cable.
(I should add that I don't strip cable every day but I learnt how to use a small but very sharp pen knife to strip outer sheaths. A bit time-consuming, but I like doing it that way as it works on any sort of multi-core cable. And the trick to not nipping the conductor is to not cut quite all the way through the insulation: let the stripping effort break the last little bit.)
I love this little guy from ideal:
the tool is a hollow tube. there's a hooked blade centered in the middle so that when you push the cable through the tool, it splits the sheath without damaging the conductors. the v-groove at the end is for stripping the individual conductors.
it took almost no time for me to learn to strip the inner conductors without nicking. and now i can strip without even looking at the wire.
