Hello Philip,
As the current 
UK-based planDisney Panelist, it really does make me super happy when I have the pleasure of welcoming a fellow Brit here to our pixie-dusted spot!
I note you've indicated that your arrival date at Walt Disney World Resort is fast approaching on April 14th, 2022.  With this in mind, it really is important to link your already purchased Ultimate Tickets to your My Disney Experience account.  Once linked, you'll be able to go ahead and make those all-important 
Disney Park Pass reservations for all your desired Disney days!
As I am unable to gain access to your 
My Disney Experience account, it is a little tricky for me to know exactly why you're seeing a message that there's no information.  
However, what I most certainly can offer are some easy to follow instructions on how to link your 
Disney Theme Park Tickets purchased from the Walt Disney Travel Company to your My Disney Experience -
 - Log in to My 
Disney Experience via a desktop computer
 - Head to 
My Plans within the drop-down menu
 - Hover over 
Park Tickets and select 
Link Tickets - Continue to follow the onscreen prompts to enter 
Ticket ID Numbers (which are located underneath the barcodes on your Will Call eTicket vouchers)
If you are still unable to link your tickets, then my best suggestion really would be for you to seek the tech-savvy assistance of a Cast Member who will be able to fully access your My Disney Experience account, and be able to link any valid Disney Theme Park Tickets for you.
To connect with a Cast Member, simply dial the UK freephone number for 
Technical and Website Support found within this handy 
Walt Disney World Resort Phone Directory.  Prior to calling, you'll want to be sure to have your email containing your Will Call eTicket vouchers close to hand.
Philip, all that now remains is for me to wish you and your whole family of 8 Mouseketeers an extra magical upcoming April holiday to the wonder of Walt Disney World Resort!  
Have a great Disney day ~ 
Jane