Cables finally arrived and I got everything hooked up. There were a couple of niggles due to the remote system for the HD switch/splitter using the same IR signals as the TV systems display settings causing great fun as it set up screen modes that netiher display could support!!
But its sorted now...HD quality images now being projected from the DVD player in 720p, using a scart upscaler, and the Freesat box sending direct to the switch.
And with the press of a button (can't use the remote) I can send the images to the projector or the TV in glorious 720p Hi Def.
I do get an occasional "pink" screen on the TV, when going from an HD channel to a standard def channel though, easy fixed by switching channels a few times but still...The coder in me does not like to see an obvious bug, but 99% functional is still pretty good, and the picture quality, with no signal loss or wavy lines is brilliant. I will see if I can shorten the HDMI cable and avoid using an extender, which may be part of the problem, but really its not such a big issue.
Movie nights will be a lot more fun with no microwave interference or image drop at random intervals.