It is better to not limit yourself to verified UK writing companies because all the writing companies work with students across the globe. Writers will find themselves presented with orders from the UK, USA, Australia, and Canada. Writers should work where they find themselves hired, and then choose their orders from within. The company does not control what orders you choose to apply for, but they do control the order assignments. Just make sure to pick orders based on personal preferences so you and the company can meet halfway. It is difficult to verify company locations. That would make it more difficult for a writer to find a company to connect with.
The opinions are that of the author's alone based on an individual capacity. Opinions are provided "as is" and are not error-free.