@helenmj - I'm fortunate enough to live just outside a town where once hosiery, knitting and underwear were the staple industries (with footwear and hats close by). Anyway, we have a funny little drapery shop - very, very old fashioned, the nightwear I'm sure my grandmother would have been comfortable with.
Anyway, they apparently have a great selection of gentle top/diabetes friendly socks at rock bottom prices. This is something that is talked about it most years in our Diabetes UK local group, when we have a local podiatrist come to visit a monthly meeting.
I think my takeaway message would be don't ignore your High Street in your quest. If you have any old fashioned shops, such as I describe, give them a go.