Thanks for your reply, If I understand you correctly; SmartTiles is closed source and focuses on the official out of the box experience of the SmartThings experience.
Thus there is no easy way for the end user to integrate 3rd party smartapps into the SmartTile experience
I was hoping I could simply achieve what I wanted to by changing a couple of lines of code. I.e. Edit the Efergy Engage code from tonesto7 and assign the current cost in £ p/hr as another power meter.
Maybe I should try asking my question here.
Thanks again anyway.