Ok, thanks for your patience with this. I will attempt to use the optimalF function and see how it goes.

I have deposited £1000 and I am ready to roll with one of my own strategies. Am I right in thinking that I am better to set the risk level so that the capital required figure comes out at about £500 to £750 to allow some room for error?

This would automatically be taken care of if I was working at a % of my account so this is an approach that I will have to get used to.