You can regenerate your login details if you forget them. On the login page Use the link Have you forgotten your login details?.
If you enter the same Company registration number and e-mail as when you first logged in, you should immediately receive an e-mail with instructions to reset your password (if you don’t receive an e-mail, please check your SPAM folder to see if it was filtered out of your regular e-mail). If you enter a different Company registration number or e-mail, your company will have to be reverified and a new e-mail with instructions will be received that same day.