FWIW, my understanding is that unless you have an exemption (certain military pilots, etc) you have to do an 'approved course'; this can be either distance or residential. So you can do less classroom time, but you still need to do some. Certainly, when you're booking for the exams, you need to get the booking form signed and stamped by your school.
There is no pure self-study option, just more or less self-study.