If you will be the sole owner of the business, you can trade as a sole trader. You are self-employed, and there is no separate business entity. You can be a sole trader even if you have employees working for you.
Alternatively, you can form a limited company.
If there will be more than one owner of the business, then you can trade as a limited company (see 2), a partnership (see 3) or a limited liability partnership (see 4).