Just a big thank you to @ShaunKZNfor this wiring diagram it was super helpful!
For the next person who comes along, if you want to use a standard USB to RS232 (male) connector then you can easily take an RJ45 cable, cut one end off and terminate it into a DB9 breakout board connector (female) eg. https://www.amazon.co.uk/gp/product/B07MQSL2P9 this allows you to super easily attach the RXD, TXD and Ground to the correct pins.
The myriad of off-the-shelf USB to RJ45 serial cables didn't work for me, I just had junk output which I presume is due to RXD and TXD being the wrong way around.