I have tried to register on My Account but it says "email address already in use".

We have already created accounts on our website for existing supporters.  This may explain why this message is displayed for you. We are progressively sending out instructions about how to access My Account to all our supporters. 

You can check if we have already setup a web account for you by entering your email address on the Forgotten Password page.  If we have, you will automatically be emailed your login details. 

Please tell us your feedback when you've had a look!