It looks like Lego has done a pretty good job of maintaining stock levels this year in the run up to Christmas:
Most new SW sets are in stock at [email protected]
There are a few with ship dates close to Xmas, and some temporarily out of stock, but there are sets available at all price points.
Dr Who (possibly one of the big ones this year, esp in UK) - in stock, as are all the ideas except Birds.
JW - a few sets, but we know there has been problems keeping these in stock.
Minecraft - again some in stock, but all with pre-Xmas ship dates (although probably too late for the big day).
Marvel and DC - stock levels seem fine.
City - again seems fine, decent availability on the Deep Sea, and even some Arctic from last year. Last year some arctic sets were OOS in the run-up to Xmas.
Ninjago - decent availability.
Dimensions - packs in stock, but no consoles (so not good).
Elves and Friends - all seem available.
So either the predicted best sellers (SW Kylo Ren's ship, Dr Who, Deep Sea ship) have not sold that well, or Lego have upped their game this year and made sure that the popular sets have not had massive outages in stock.