Thanks for all the comments chaps, they do spur me on.
Talking of which, had a home alone day today which resulted in about 7 hours work on the interchange. Unfortunately, there doesn't seem all that much to show for it.
The Cliff Barker gauge 3 track is fantastic (especially considering it's cheaper than a lot of G scale stuff at £11 a yard), but straight out of the box it doesn't look particularly authentic with it's jet black sleepers and stainless steel rail. When I was at Steve's yesterday, I saw this stuff and decided to give it a try.
WARNING - I WOULD DEFINITELY NOT RECOMMEND DOING THIS WITH TRACK POWER!!. The dyes are pretty expensive, but the track is looking much better now, especially around the pointwork. I have wiped the dye off the top of the running tracks. Unfortunately it doesn't show up too well in the photo. I've just sprayed an LGB buffer stop with the oily brown as well, so I'll let you know how that comes out.
I also bought a couple of sheets of brick effect plastic card, so the platform is now edged properly. I've used the same stuff to edge the elevated siding and ramp. It's actually only 3 bricks high, but I've cut it at 4 bricks so that it will help to keep the ballast in place. Funnily enough the track that I built yesterday looks very similar to the way the gauge 3 track looks now in the photo although I haven't sprayed it due to it being used for track power.
The ramp has been laid in concrete. The pins are holding the plastic card in place until the cement cures. When I remove them, I'm not certain that the plastic card will stay in place, but if it doesn't it doesn't really matter because the cement will be imprinted with the brick pattern.
The concrete is a bit rough, but will eventually be hidden under the ballast.