Hi Seafian..
I've posted a PM to you. One thing that slipped by me is that if you look at the PDF for the Project, it marks IC3 as S201S02 in the circuit diagram but in the component list, it is marked as S201S01.
I'm now wondering which one is correct and based on this, which substitute do I use?
If only I could get my hands on the datasheet for the S201S01.
It seems from trawling the internet the that the following are alternatives:
S201S05 for the S201S01 and the S201S06 for the S201S02
Regards
Declan