I can’t find a edit feature so here is an update.
I found the pressure switch, it was hidden away on the right hand side. I found it easier to take off the right side casing of the machine then you can run it up and still get to things. I took the pipe off blew through it from the switch end and could hear it blowing out at the other end. I run it up a few times with the side off and could hear the switch click as it was filling, it didn’t throw up the error so hopefully it has cleared the fault. I kept some bits out of our old dishwasher which was also a hotpoint but the switch had a different plug on it.