Startup Overseas Forums

I am starting up a business to sell framed pictures. I am resident in France and am registered as an auto entrepreneur. My e-commerce website will go live soon. As an auto entrepreneur I am not VAT registered. Can I simply export to potential UK customers? Any special paperwork needed? Also, I would like to participate in Christmas fairs in England. What do I need to do to remain legal? Can I sell to customers at these fairs?