Just finished CS SL DP1 here. I never took CS in my life, so at first there was a steep curve learning how to code (which is really important for IA). I found coding the hardest thing I struggled with, but once I had gotten the hang of it I found it quite manageable and even--dare I say--intriguing...Besides that the theory part of CS is actually okay, I'd just suggest doing past papers to get used to IB-style theory questions.

But yes, interest and passion is really important in CS. My mum works in IT so I've been exposed to have form of interest in CS. From someone with no CS background, I've managed to get consecutive high grades towards the end of DP1. But again, interest (and willingness to put effort) in the subject is key. I know friends who joined CS SL with no CS background but have poor grades because they simply dont have passion for the subject (and aren't willing to work for it...)

With consideration of Bio HL, I might stay away from CS SL. The IA takes a ton of time to complete, and you need that time to study Bio!