When picking a work experience placement it is always useful to consult your teachers for advice and help with what to do. If you do struggle to find something that is right for you, you can always ask local businesses if they will take you for the week. In this case it is very important that you tell them the dates of your work experience.
When preparing for your work experience you should always take travel into account and should know roughly the time it will take to get to your placement to ensure that you arrive at the correct time that you have discussed with the person supplying you with your work experience. To do this you must travel to and from the business a couple of days before you are to go work there. This will not only help your confidence in travelling there but will also mean you should get there on time.
When deciding what to wear the most important thing to do is contact the business that you will be working at and ask them what is appropriate to wear.
If your place of work requires you to submit a CV then what you could do is find a template online and use that to help you. In addition, if you are struggling you can write down a list of the things you have done (e.g. extra-curricular activities).