I'm not in the UK, but I thought I'd share my thought about batting--
My all time favorite is Hobbs wool. It's on the pricey side, but it quilts beautifully. I have a flannel quilt with wool batting on my bed that gets laundered regularly and have not had any problems. There was a tiny bit of shrinkage when it was laundered the first time, but not much. I also like Hobbs 80/20 and I use it often. I don't pre-wash or pre-soak any of the batting I use. The little bit of shrinkage isn't a bother to me. I kind of like the old fashioned look. I launder my quilts in a washing machine with cold water and I dry them in the dryer on a regular setting.