I haven't dried it but have frozen it successfully in a plastic bag - washed but left whole and straight into the freezer. You can then use as much or as little as you like in cooking. I should imagine you could dry it like drying flowers - by hanging bunches of it upside down in the airing cupboard for a few days/weeks.

Yup! That's the way, Cammomile. I have bunches of herbs hanging upside-down in our boiler house - keeps tasty additions to stews etc. going all through winter and beyond.