We can probably faultfind it over the internet but unlikely to be able to repair it.
Does the pilot light come on first stage, but then go off when you try to twist the lighting knob to the second stage?
If the pilot doesn't come on at first stage, can you see the little spark from the piezzo spark generator when you push the lighting button?
If you've followed the lighting instructions to the letter, and it won't go on, I'm afraid its likely to be a heating engineer/plumber job. And better to get on the phone sharpish as they are gonna be even harder to find over Xmas.