i wondered if anybody has asked this b4 and sorry if they have but is there somewhere on this forum a thread or link for preparing your vehicle for long journeys e.g holidays etc ?

I couldn't find anything in search for you, but here's a list of things I always check before any long trips:

1. Tires and spare tire pressure
2. All fluids: oil, water, transmission
3. How long/how many miles since last tune up? Possibly need to replace plugs/plug wires cap & rotor.
4. Clean battery terminals and check condition of battery

There are a couple things on ETS that would help you make sure you have the right gear with you:

Recommended Auto Disaster Kit:
http://www.equipped.org/earthqk.htm#erthqkcarkt

Doug's blog entry on the Kim Family talks about Car prep:
http://www.equipped.org/blog/?p=43
(Shows a picture of what's in the back of his vehicle)

There is one issue I'd take with Doug's blog entry on his car packout. He says, "Since the weather is almost always mild or warm here in the desert southwest where I reside, there’s no cold-weather specific gear in my everyday car carry like there would be if I lived elsewhere."

I would counter with the fact that even in the desert sw-US, deserts can and do get cool to even downright COLD at night depending on time of year, rain, etc. "Almost-always" is what almost always gets folks into trouble. While I wouldn't think you'd pack for northern winters, some basic cold weather gear may be in order...and he touches upon that later in the text.