The Food Information Regulations 2014 cover the requirements relating to ingredients and allergen labelling on food (including drinks) that are prepacked for direct sale (PPDS) that are in force from 1 October 2021.
More information regarding the requirements for labelling these foods can be found on the Food Standards Agency website. There is a decision tool to help determine if your food is PPDS - Allergen and ingredients food labelling decision tool | Food Standards Agency and there is also lots of detailed guidance on the requirements to label PPDS with the name of the food and a full ingredients list with allergenic ingredients emphasised - Allergen labelling changes for prepacked for direct sale (PPDS) food | Food Standards Agency
For businesses selling prepacked food, The Business Companion also has useful guidance on the direct sale of pre-packed and other non-prepacked foods.
The requirements are enforced by Hampshire County Council Trading Standards who offer a range of chargeable business support and advice services for which you need to register, the site includes further details about their fees and the terms and conditions of the service.