Yes there is. Go to the website homepage.

On the desktop site there is a "Manage/Check in" tab at the top of the flight search box. On the mobile site it is just below.

Click that and enter your 6 character PNR as the booking reference, and your surname.

You may then be asked to enter a One Time Password which would be sent to the email/phone number in your booking.

After that you are in Manage Booking!