Firstly, these are large for UK sizes.
The size (10 UK) = (10 UK / 11 UK Women), fits like a 11 or 12 UK/EUR size. So, I would suggest ordering 1 or 2 sizes smaller than your actual size. One size smaller if you like to wear loose slippers, and 2 sizes smaller if you like fitted ones.
Secondly, there are two different sizes to order from. But they were similar in my experience. Ordering from either option will get you the same size pair. For example.
(10 UK) = (10 UK / 11 UK Women).
But don't get confused with the sizes printed on the slides. I think the slides are based on the US/Canada sizes and the printed is for the US, Canada, UK, and Europe.
__ Size printed under the sole
M 10 - W 12
__ Printed on the tags
I'm only taking 1 star away because of the confusion with sizes. The video is attached here for reference.
I hope you will find this review helpful.