I have a mate who has struggled off and on for the past 18 months or so self studying. He should write a book on how not to do it I think.
Tried with the notes from Bristol, then took himself off to see someone at Cranfield, then got some more notes or books from somewhere. And the entire time he didn't bother following the lesson plan for any particular one. In the end he settled at GTS in Bournemouth and pretty much had 1 to 1 tuition off and on in 1-2 week spurts over about a 6 month period and then fitted into their consolidation courses when they came around. Think he only has 2 exams to pass now and a few sittings left so fingers crossed and good on him for sticking with it.