I finally got off my bum and started sewing my bag using the tutorial from verypurpleperson. As for the choice of fabric, I settled on some cute red hippo cloth and a somewhat more "normal" rose fabric, both from Ikea.
Using the pdf pattern was really simple with markings to tell you exactly where to join up the pieces of A4 paper. The original bag tutorial did not have any pockets, so I decided that this was a good time to learn how to sew zipper pockets and attach it to the basic bag pattern.
After a few hours of fiddling, here's my version of the reversible bag: