Corfu is back of the Greek Nation, which is part of the European Union. Therefore you can bring back as much as you like from wherever you like in Corfu (provided it is for personal use). Her Majesty's Customs and Excise usually apply their own rules as to what that means. It is probably true to say that it is impossible to break the rules with what you can carry in your personal luggage etc. If you bring back a packing case full of tobacco, that might be considered "pushing your luck".