Is Amazon custom available in UK?

Hi,
We want to sell our personalised products using Amazon Custom. But when we try and register for this in the UK we can’t. The message when we sign up on this page:
https://sellercentral-europe.amazon.com/customization/manageCustomRegistration

Says:
Thank you for your interest. Unfortunately, Amazon Custom is currently not available in your selected marketplace. If you have a selling account in a different, supported marketplace which you’d like to enrol, please make sure you are logged into that account and re-register.
In order to join Amazon Custom you must have a professional selling account. Please switch your plan and re-register.

Could you please tell me if we can sell customised products on Amazon UK like this one:

We have tried to sign up but can’t seem to manage it.

Anyone who has managed to do this could you get in touch please?

Bob