I've been wfp for over 10 years and i carry loads of spares. As Vin said,everything but a spare tank. Clips,connectors etc will all fit in your glove box. There are a couple of window cleaners in my area who don't have a spare anything and they always ring me. The other day a goose neck, someone else 'o'clips. All these bits are pence. Better than driving all the way home. Imo.
I've even got a spare van. I needed it when i used to have a Trafic