Buy Domain Name from Office 365

Hi, 

It appears you can only purchase a domain name from Office 365 if you have an Office 365 subscription. We plan on purchasing Office 365 at a later date, but wish to have our own domain name beforehand for use with CRM. 

Is there no way to purchase a domain name without first purchasing the Office 365 licenses? And if not, where is the best place to buy a domain from for compatibility with Office 365 / online services? (UK)