You may need a visa to come into the UK, depending on your nationality. Information on visitor visas and how to apply for one can be found on the UK Border Agency website.
Following the recent referendum vote for the UK to leave the European Union, visa-free travel is still in place for citizens of member states of the European Union, including to and from the UK. Any changes to visa-free travel are unlikely to take place in the immediate future.
Delegates must be registered and have paid in full for the event before applying for a VISA letter. Invitation letters can be requested during the registration process, providing Passport number and Country of Issue.