It sometimes feels like you need a suitcase to go out with baby - especially on your first outings with baby. My advice is have everything that is non perishable in your diaper bag stocked. Don't wait until the moment you leave to stock up. Keep it simple and have a a few test runs close to home. Soon you'll see only a few good accessories and you'll be ready to go.
Baby Jogger City Mini Pram is great - single hand fold and very versatile;
Lassig Urban Nappy Bag has everything you need on the go;
Skiphop Pronto! Changing Station is a small, throw in your bag or boot changing kit if you don't want the whole nappy bag solution. It has space for everything you need - a change mat, space for wipes and nappies;
Nook Organic Cotton Blanket;
Manduca Baby Carrier;
Maxi Cosi Euro Car Seat