Depends where we are going - now the kids are 2.5 and 14mths I just take out a nappy change kit (which DH skillfully put together, essentially its just 4 nappies per kid, wipes and nappy bags) and that fits perfectly in the under carriage compartment.

Otherwise I'll adjust the nappy bag strap or just rest it on the hood.

I think there are side bags you can buy too which may help? I had the bum bag style one which was great but DH lost it!