Under section 1 of the Employment Rights Act 1996, certain particulars do have to be put in writing within 2 months of the start of the contract. The “written statement of employment particulars” advises the employee of the more important terms of their employment. There is no “small-employer” exclusion from this legal requirement.
Within two months of commencement employees should be supplied with the terms of their employment in a written document such as an employee handbook. The employer should make it clear if the hand-book does not form part of the contract. If parts of the employee hand-book are contractual this should be shared with the employee before they join the company. It’s much easier having a “non-contractual” employee hand-book because the policies and procedures can be varied much easier.