I helped a younger friend do this - in fact he is still doing part of it, started about a year ago but has other work.
He has done it through a group where he has a support tutor via email and then all the books etc
He is severely dyslexic and I helped him to learn to read years ago and had fostered his interest in computers. Our experience was that all the info from the organisation running it was both helpful and accurate.
The time taken will depend on past knowledge and the time available. Perhaps allow about 2 hours per chapter - we did find that there was some duplication across the various modules, so then some of the modules take virtually no time. The student and I developed some visual (mind mapping style) diagrams as it suited his learning style and though he is now able to continue independently, he did say he was continuing to use these techniques. Do contact your tutor if you get stuck - they are helpful especially when some questions seemed ambiguous. The ambiguity confused us - eg questions where they seemed to want one answer yet the student saw 2 possibilities - and it usually seemed that we were on the right track and seeing the two options was wanted. It was very practical and the lad involved has now started a business and is fairly busy doing IT work, mainly hardware related. It is useful either to be working near IT technicians or have access to some for practical back up.