Model is 5'6" tall (167cm), and wearing a size UK 12. She would usually wear a UK 10, so, as you can see, it's a bit big on her.
As regards the stated sizes, the cm numbers refer to what is given on the labels for bust size. In brackets you will find a UK women's size conversion.
For US women's sizes please subtract four from the stated UK size, so, for instance, a UK 12 is the same as a US 8, and so on.
Concerning the lengths
Regular are intended for women between 160 and 170cm in height, or, roughly, 5'3" and 5'7"
long lengths for women between 170 and 180cm in height - roughly 5'7" and 5'11"
extra long lengths for women between 180 and 190cm in height - roughly 5'11" and 6'3"