I'll answer my own post in case it will be useful to someone.
I have figured where I was going wrong, it seems obvious now but not at the time of posting.
Although I was launching the bot mod I was not using the plutonium launcher.exe but I was starting the mp.exe from the game folder to get to the host game menu.
And yes, I needed to install plutonium (registering a different user at the forums) and the bot files onto the other pc.
