The rules are different for sole traders and for companies.
Generally sole traders can NOT claim for eating out. Eating is not ‘wholly, exclusively and necessarily for the purposes of business’ because it fulfils the dual purpose of keeping you alive!
Employees of limited companies can claim if the meal is wholly and exclusively for business purposes. If business reasons require them to be away from home/office around mealtimes (so that they are unable to make their usual arrangements) then it is a reasonable business expense.
The amount they can claim for a meal will be agreed with their employer but should not be overly lavish and I would suggest limiting alcohol to one drink with the meal.
Entertaining is generally not allowed (see other Tax Tips on staff entertaining) for tax or VAT purposes