I logged into the game via the game client ( not the launcher ) and saw I had a message in my inbox. I clicked on the link and was taken to the message centre, read the message but now I cannot log out of the website. I keep getting "access denied" messages including an error reference of 1020.
Problem solved. I had to log in again to send a support ticket and I was then able to log out. I'm now able to log in an out again as normal. I won't click the lobby link to read messages again!