This isn’t cheap but it might well be worth it, and it’s kid-friendly too. Seems like a good way to check out cycle touring (especially if you want to take your family in future) and you get to go places that aren’t normally available to the public.
Big Coast is an entry level, non-competitive and family-friendly two-day mountain bike ride through some of the Wellington region’s finest scenery. Recall a bygone era on the Rimutaka Rail Trail then camp overnight next to Lake Wairarapa.
The second day is a spectacular journey round the south coast through normally in-accessible private land, to Eastbourne. But you can just take the one day option if you like.