Thank you all for all your really helpful replies - it definitely sounds as though Club is the way to go so we just now need to book the seats.

My only remaining question is whether we should try and book an infant seat at T-355 days with a "Baby EfficientTraveller" name to ensure we snag the Club bassinet seats and then do a later name change as I am concerned that the bassinets could go before the little one is born. Has anyone had any experience of doing this?