The differences between building control and planning permission can be very confusing as a general rule if your are building a log cabin that is going to be a residential home where people are going to permanently live, then it is more likely that you are going to need planning permission for this log cabin. The best advised is to approach your local planning office and inquire if you will need planning permission for the building before you go ahead with the development of any log cabin or garden building. With building control regulations this is an approval and a safeguard that of any building work carried out is done in accordance with all building regulation currently in force today. If your new log cabin is just a garden cabin for leisure or is just going to be used as an office, you may not need building control or planning permission but it is always advisable to check as the location of your cabin can make a difference.
For more information on planning and building permission go to the government website.