Antenatal for us in April too, felt too early when I booked it! We are going for NCT as its our first and thinking it will be good to meet people as well as getting more info.
My in laws have been really supportive, careful not to give advice but always asking interested questions. I'm trying to think of ways to involve my MIL more and help her feel useful.
Neither family has yet made any noises about how long they plan to visit for once the baby arrives - my family are a 2 and a half hour drive away so I'd expect them to stay but hoping it's a couple of days at the most, especially if that's when my DH will be off.