I received this email below from the National Lottery.
Please note that from 13th December 2010 we will be making some changes to our Terms and Conditions and Rules.
Summary of upcoming changes:
As well as being a UK or Isle of Man resident, to play National Lottery games online or by text you must be physically located in the UK or Isle of Man when buying a ticket.
If you play by Direct Debit, you must be physically located in the UK or Isle of Man when setting up your Direct Debit Account and also when making amendments to it, including buying additional tickets, or changing your numbers or payment details. As long as you only make these changes while you are physically located in the UK or Isle of Man, your tickets will be valid if you travel overseas.
If you do not meet these requirements, any ticket purchases you make will be invalid and no prizes paid, and we will have the right to reclaim any prizes already paid under these circumstances.