Yes thanks Woodenspoke,
I have been thinking about the feeding of the board under the sander belt and thinking I might be better to have the wood fixed down sitting against a stop block. On the ends of the 2 lengths of angle iron mounted to the sander, I could have some height adjustable Castor wheels then the Sander can be freely moved around while maintaining a fixed height above the wood.
This could be a lot safer solution as you then have full control of the sander with your hand on the trigger switch.