Paddy, I have mostly built aircraft over the years. Armor was a little bit here and there. The big scale stuff that Tim and I are building now is all new. Some of it is quite reasonably priced for what it is. Recently I pondered on Trumpeter's Tiger II for quite a while then finally hunted till I found a price point on it that I decided I could live with. The box for it is that of a large suit case and I could easily put almost all my Das Werk kits inside that box. Thing is, as large as that box is, the built tank is sized between a 1/12th car and a 1/8 car but has more detail than I would ever be able to display. Pondering on getting info on the big overhead cranes and building one of those to have the Tiger II open for rework. The Tiger II V2 is still in existence and they are in process of restoring it to full running and operational condition with posts on Utube. Then there is another Tiger II #300 that is running around as well. I have had no info on any of these, but have been able to go online and find plenty of info.
The 1/16th sFH 18 I am currently working on was started with no info at all. All my build info came from online searches which have given plenty of info to do all the rework I have done.
Age, I will be 70 in January. Am still working and will probably be doing so for at least a little while yet. I guess I am lucky for the health and abilities I have which are still holding on well enough. Was having some minor memory issues, but have changed my diet a little and that has gotten a whole lot better. Just need to get to bed earlier to get enough sleep.
As to building, I just don't rush it any more. If I am dealing with issues or problems, I ponder them for a while. Usually do my major building on weekends (not this Saturday, going to an airshow WWII aircraft Woo Hoo!)
The most boring part of building a tank is the tracks, and I just situate up, put on a video or two, get the parts organized into piles and go through each part in each pile and clean it up. Then I do 10 link assemblies, but only up to what will fit a full length of track. If I have a track that uses 77 links, I build seven 10 link sets for each track. Then do the individual links to flush it out. Have found that the number in the instructions might or might not be right, and now try to keep the tensioner part loose so that it can be adjusted.
I am enjoying these builds more than I have a lot of them over the years which is why I have been obtaining the 1/16th scale kits a lot lately.
You might try one of the Takom 1/16th scale Jeeps. They are reasonably priced, have all the parts (engine, suspension, transmission, etc) and yet are in the car category, yet you can weather them up or not, up to you.