Stephen, I started on these about 6 months ago and plugged away with help from this forum. I worked up to it via (after years of Grauniad cryptics) the Azed in the Observer. The old/Scottish/dialect etc content and necessity for Chambers are similar. Azeds are freely downloaded from the Grauniad site and I did one a day for a while. It really helped and now some of the arcane words keep popping up (eg uts) regularly.
Still a way to go but enjoying getting there (I don't often have to wait for the official solution to be published any more - thanks to the resident wizards here!).