Partnership - You carry the risks and now must work with others who can let you down. Although not compulsory, approach a solicitor and set up a partnership agreement. This even applies between family partners. Each partner has unlimited libaility for the business's debts. A legal entity separate from its owners.
Profits are subject to corporation tax.
PAYE and national insurance contributions must be administered for employees. The business's name should project its identity and image. You will need letter-headed paper, business cards, invoices, order forms etc. A sign on your van or factory unit will be useful. Make sure your logo communicates the company well.