Is it legal to buy milk powder from UK shops and sell it on-line to china customers?

I have the opportunity to expand my business by reselling milk powder to China. I know that there are restrictions (a customer can buy only 2 milk powders per day in Tesco or any other supermarket) but those are not a problem to be followed. So, is it illegal to buy milk powders in UK and resell them overseas (or UK) ?