Iris & LillyWomen's Cotton G-String Knickers, Pack of 5

Will they fit on me I'm a size 6 UK

I am a UK size 12 should I order medium or large?

Do these thongs go into a string or are they a strip. i'm size 16 should xl should be ok shouldn't they. i normally buy from asda and they use sizes.

What would fit a 20 UK