Hi from a bit further east downunder.
I'm modelling in 15/16mm to the foot and G scale, using 32mm and 45mm gauges. I love building track (in addition to saving cost; a simple turnout/point costs me around US$20 max.).
If you want to use 45mm gauge, then you would have to go to 7/8" to the foot if you want to model 2ft or 2ft 3in with any pretence at realism. If you do this, some of my dimensions will need scaling up.
The Talyllyn Railway (which may be one of those you rode on) is my favourite. I'm not sure about current practice but on the original railway, plain track was supported on every third sleeper by base plates which in turn were spiked to the sleeper. By using this technique, a very rigid track is formed, and th rails cannot creep. I'm planning to use method this very shortly for my 2ft and "2ft 3in" trackwork (32mm). It is the method I have already used on point work, including dual gauge ones, where good alignment is essential. (Note: the F(f)estiniog railway uses chaired track.)
Base plates: I use K & S thin 1/4 inch strip cut to suitable lengths with good quality shears (very quick to make)
Timber: I use either yellow cedar (one of the most rot resistant timbers) or treated pine, in both cases coated and/or soaked with a preservative. The cedar probably does not need preservative, but I use it partly as "belt and braces" and partly for cosmetic reasons. In my scales, I use timber 12mm wide to represent 9 inches prototype which is about right. I use timber 19mm deep (it is a standard dressed timber size at least in these parts) and it takes the full length of spike. Once ballast is added, it looks fine, and is that much stronger and will take longer to rot. A good length for 45mm gauge is about 4 inches or 100mm
Spikes: I have happily used Sunset Valley blackened s/s spikes. They do as has been said tend to work out - sometimes, not always - I think a dab of araldite would deal with this (untested). I found on Ebay some miniature spikes which screw in, and these don't work loose. I don't have the url to hand. They are I believe stainless, and they are blackened, and are particularly useful for repairing track in situ, because they don't require hammering. I am now standardising on the thicker variety of these. Btw, I always pre-drill holes with a 1mm drill in a battery powered Dremel tool.
Rail: I started with code 332. If you are using 7/8" scale, this is fine. Otherwise I strongly recommend using code 250 flat bottomed rail. Code 332 looks wrong and is grossly over scale at 1:19. I've used (Peco) code 200 for complex points and the over engineered LGB wheels will happily run on this without the flanges bumping, so code 250 is more than enough. Living where you do, it is unlikely that elephants will be walking on your track (I'm referring to an LGB promotion). I'm even going to use rail down to about code 180 for sidings.
Sorry, no time for pics at the moment. I can be contacted off list at
bruce@beethoven.nz, as I don't monitor this site regularly - although, if contacted, I may well post a reply here,
Bruce from Auckland, New Zealand