Carry bags
How often have you seen the family walking down to the beach with the dad trailing behind with all the gear pile up on top of him like a pack mule. Let’s face it… it will be you that will carry most of the load so you may as well be prepared.
Your wife/partner might like the idea of a ‘sling over your shoulder’ nappy bag, but I find the best way to store all that stuff is a sports backpack, because 9 times out of ten you end up being the one that chases after your energetic kid and you need something that works with you, not against you. Wiggle sell some cool and practical backpacks and Bagworld have a massive range.