Sorry to hear of poor growth so far but you have experienced two hugely different autumns and your first one last year was exceptionally mild and untypical. This year was on the cool side, until recently but this is exceptionally warm again, for the time of year, and as you say it looks like turning colder by month’s end.
I am cautious of seed packets’ advice, yes you can sow at those dates for sure, but will results be worth using precious space for? I think the first three lettuce are soft-leaved roundheads, not easy for leaf picking, Maravilla is better and worth trying esp in your warm kitchen. Then once going, lettuce plants can stand cold weather when protected from wind, rain etc, so good luck and Happy New Year too!