Looking for yarn to make 'Sophie' bag

I want to make this bag:


Im still struggling to understand weights of wools but am startign to get my head around gauges - am i right in thinking that an aran would be to big and DK would be to small?

can anybody suggest a nice feltable worsted weight yarn available in the UK?

thank in advance

Cascade 220 is a great felting yarn.

I have felted with DK and it works fine. The fabric is not as heavy but for bags and scarves it works. I’ve often wondered what would happen if you double starnded DK then felted… I might have to try a swatch. I have bought some large cones of DK New Zealond wool from e-bay and wondered if it could be double stranded and felted for clogs/