When at secondary school you will have at least one opportunity to go on a work experience process. This process is when you chose a place that you wish to work in for a week or two and will attend that work place instead of school to experience life in a working environment. Some schools will have a list of places that you may wish to carry out your work experience but you are often allowed to contact your own choice of company to ask if they would be able to accept you.
When choosing where to do your work placement, try and find something that you think may interest you as a career. Work placements can not only be a great way to trial out a particular industry to see if you like it but to also gain important experience and possibly even contacts you may be able to use in the future.