That is a personal decision, I will try to provide some context.

Biostars handbooks provide a practical introduction for doing specific kind of data analysis (bioinformatics has become a vast field and no one person is going to be able to become an expert in all areas). I am not familiar with the book you mention but if it is a text book it may provide a theoretical introduction to field (may still be useful). Bioinformatics is a rapidly changing field so once you have your basics squared away you may learn more by following online forums/publications.

Do you have an exceptionally strong programming (and enough biology) background (at least one language)? If not, you may want to start learning a programming language (python/R would be good choices) in parallel. Unlike 15-20 years ago when there were not many formal bioinformatics degree programs, there are plenty around the world now. You are going to be competing with the graduates of these programs for jobs/knowledge/opportunity.

If you have strong desire and application to do this it would be possible to do. But keep in mind that this may take time (as in > 1-2+ years) and you will need to be patient.

Note: I did read your other post and appreciate that you have unique personal challenges.

If you've got a bit of R and you are comfortable with a range of biological ideas, I'd suggest having a look at "Modern Statistics for Modern Biologist". The online version is available for free here http://web.stanford.edu/class/bios221/book/index.html

If you want to improve both your programming skills and learn more about bioinformatics concepts then I recommend Rosalind: http://rosalind.info/problems/locations/