The whole concept of crosswind landings never came up during my training. I would consider that a fairly major ommission.
My home airfield has multiple runways and I guess I was lucky with 'away' landings so I never had to do one with a crosswind component of more than a few (maybe 6?) knots.
I have telephoned ATC a couple of times since then to ask for a crosswind circuit but both times it was 'not convenient'.
Being something of a fair-weather pilot it has not been a problem so far, but one of these days ....
Similarly to previous posters in this thread I was not trained on leaning techniques. I found my cross-channel checkout (with a different instructor) useful for that.
One thing I regret is the number of post PPL hours I wasted by avoiding the unknown. e.g. my first MATZ penetration - a trivial operation once you've done one, but for some reason I found the whole idea daunting beforehand.
Luckily I realised what was happening and then made a conscious effort to try something knew on every flight (no sniggering please). Flipping through various books (mostly Thom) it was amazing how many things I had learned and answered questions about but never actually done in the air. It worked wonders for my confidence and I recommend it to all recent PPLs.
Cheers,
TG.