I would never recommend a partnership for a business. As a partner you are jointly and severally liable for the debts of the partnership. The worst case scenario is that your son runs up a huge debt and does a bunk leaving you to pay it off. So I would recommend a limited company for the restaurant and get a shareholders agreement drawn up by a solicitor. As for the social work business being a sole trader may well work. Just make sure you have all the necessary insurance.