You must contact the Course Provider you have booked with as soon as possible.
The Course Provider should be able to confirm that you have successfully booked a course and give you the relevant details i.e. time date place etc. You should carefully keep any correspondence from the Course Provider until, at least you have completed the course.
If you cannot remember the course provider details, go back to the police force that sent you the original offer and they should be able to assist.
If not, consider contacting us.