Hello Mr G and welcome on board!
Sounds like you're in a similar position to me exept that I am restricted to a 6' 6" by 4' board. I'm playing with XtrkCad which is OK, if a little unwieldy at first but OK after you get more familiar with it (took me a while!) but I've already realised that my desire for double track is a little unrealistic, so I'm trying to make things more interesting elsewhere on the layout. I may give D-rail a try. Another recommendation is Winrail.
I'm also modelling diesel era, but restricting it to late 60's to mid-80's (might narrow it down later on). I have no recollection of the late 60's myself but couldn't resist incorporating the diesel hydraulics which have always held a fascination.
Anyway, good luck and look forward to reports of progress! There's plenty of advice to be had here on the various forums, so enjoy.
Cheers
Sulzerjev
QUOTE (Mr_G @ 19 Jun 2008, 20:49)
<{POST_SNAPBACK}>I have to say that I am most partial to OO guage, I have been in to model railways ever since I was a small boy, but have never had a permenant layout, Since I bought a house last year I have been working on a layout in my loft, not yet got the base boards complete but have started them. I have designed my layout using D-rail a program that I found on the internet, which I must say is very good. The layout has come from my imagination and is yet to be named, I do not have a favorate period of time and have many steam and diesel/electric locos. It has to be said that I am quite partial to Class 43's, don't know why, just love them.
I have a few projects on the go at the moment also but they are other stories.
Cheers.