Hello and welcome!Ooh! Chicken jackets. I like the sound of that! Have you used them at all?
We are in New Hampshire, USA, and we have used chicken saddles as they are called. More like an apron really.
I found some on AMAZON UK for you:
https://www.amazon.co.uk/s?k=chicken+saddles&ref=nb_sb_noss_1
Hope this helps!