UGG BOOT OWNERS, PLEASE HELP!?

I'm getting a pair of ugg Adirondacks for Christmas but I'm not sure what size I should get. I'm thinking of getting a 6.5 (UK) but how do uggs usually fit? Are they generous or smaller than other shoes? I'm about a size 6 but I want to be able to wear them for a few years as they are expensive but I would like help on the sizing. My biggest foot is about 23cm (roughly 9 inches) and the width is 9cm-ish (roughly 3.5 inches) but I have quite pronounced toes. Please, any real-ugg boot owners, can you help me?