I was about to join the group forming around this aircraft before it was put up for sale. Never did get to fly it in the end.
Definitely, definitely do some dual on a Thruster. I recommend Bertie Grotrian at Wing Farm near Warminster, although he's only available until the end of May.
The difference in inertia between a microlight (which a Luton essentially is) and a light aeroplane will be a great surprise to you even if you expect it. I came from a Condor (a two-seat Turbulent, basically) and was caught out quite a bit so a PA-28RT is likely to be an even bigger step.
But good luck! I'm so jealous. I miss my Condor and farm strip flying SO MUCH. You're gonna have so much fun.