To be fair, I've only been sewing for a year and never finished a Cashmerette patterns for advanced sewists before. Only (confident) beginner. My friend told me to get the course and that was definitely helpful but I feel I've been going from the instructions to the tutorial and back a LOT. Especially for me toile, I had to do a lot of seamripping because it's really really easy to get a pattern piece upside down.
But... in the end, I made a swimsuit, for the first time ever. And also for the first time ever, it fits great. I'm tall so I'm used to stretching the fabric of store-bought swimsuits to the max but with this pattern, I just add 5cm at the top and 5cm at the bottom and there's no stretch! Amazing!
So I would recommend the pattern but if you're like me, get the course as well because it's so much easier to see it done than to just guess from the instructions.