The rules regarding
pay are clear: It's illegal for an employer to deduct money from an employee's pay, under such circumstances, unless there is specific provision for this in a written contract of employment, or the employee has otherwise agreed to such an action, in writing, prior to the incident taking place:
http://www.direct.gov.uk/Employment/Employees/ Pay/PayArticles/fs/en?CONTENT_ID=10027228&chk= %2BjJLLe
As far as
tips are concerned, the law regards these as (taxable)
gifts direct from the customers to the staff. In which case, the employer has no more right to take money from these gifts than he has to come to your home and take away one of your daughter's Christmas presents.
Chris