Taking the first steps
Company structure
Your new business is going to need a name. You also have to decide on a structure, e.g. sole trader, partnership, limited company, etc.
Business structures
For information on which structure might best suit your business, the Gov.UK website has advice on setting up as one of the following:
Business names
If you decide on a business name that's already being used, you could face legal action for trademark infringement, potentially being forced to change your name and pay damages. Even if the names are different, similar names could still cause issues if they are in the same industry or if the other business has established a strong reputation.
So it is wise to thoroughly check if it already registered.