Two lovely friends have booked this for a treat for me and I'm looking forward to it, but what on earth should I wear? I live in London so can access quite a lot of shops. I'm size 18/20, hate my upper arms and have no proper waist. Legs are ok. I'm 40 and really don't want to look frumpy. Would like to blend in. Any ideas? Has anyone been there recently and can tell me what they wore?