I am currently taking a Maya Animation online course through Escape at the moment.
Obviously not the same course. I took it to fill the gaps of stuff I could not work out for myself and get some of my work critiqued.
The online course I assume is the same layout. Videos and attachments to take you through each bit step by step. I cant comment on the zbrush course directly, but I am going up to the studio in June to get a better idea of what they do and what they can do for me in my career and progress further.
I have been doing the course for two months and is open for a year so I am glad for me it works, speak to them mate. You might be able to find most of the tutorials online and bits on youtube and go from there.
Good luck