Hi Roger
On Sunday 11 Apr 2010 22:22:14 Roger Munford wrote:
> Will have to learn from scratch but I hope to be able to quickly produce
> a simple 2D plan of my roof showing position of rafters,  rooflights etc.
Have you looked at QCad [1]? I was looking for a similar program to my dad 
while trying to tempt him to Linux (he's stuck on Windows for TurboCAD), and 
it seemed pretty good.
You can get the community (open source) version for free, I'm not sure what 
you miss out from the professional version though.
Cheers
Mark
[1] 
http://www.qcad.org/qcad.html