I did NCT and NHS.
NHS - What is available in that hospital, their policies, some discussion of pain relief pros and cons, breastfeeding chat, child oral health chat (our area has worst teeth in country apparently),tour of ward and how to get in out of hours, good-bye and thanks. Was on a Saturday, no lunch or room to eat it provided, so no oppurtunity really to speak to anyone. Very midwife led. Also covered 3 months of due dates.
NCT - More relaxed. Teachers provided the basis for detailed, open discussion on all sorts of birth things - bf'ing, chemical pain relief, positions, lots of role plays, what dads can do, managing expectations, nappies, lots of baby care stuff - nothing I didn't learn at hopsital or from books really, BUT - made soem fabulous, like minded friends, with nwo with babies born within 3 weeks of DS. Also, role play of CS really prepared me for my em cs.
I benefited from both tbh.