I had a similar foundation dilemma and spurred on by a friend I approached the YSL counter. The assistants couldn't have been friendlier, knew immediately which foundation and shade would be best for my skin, applied some for me to see and sent me away with a small bottle of that shade to try at home, telling me to come back and buy when I was ready. I was pleased that there was no hard sell and of course I returned and purchased, and have returned to that counter since.
How about Boden for tops? I still get basics from there and returns are easy.