Good on you Matt.
You've taken a good outlook from the start with your ute (which I might add, I like

), I have to agree with
"Wrongway- Trev-fuzz" 
as well...keep the ute on the road & do bits at a time. Sand or soda blasting is great on a off road re-build but can be devastating or impossible to do to a car that you may want to drive around... (this said if you have spare panels ie: doors, guards tailgate & bonnet you can pick the best of these and get 'em blasted off the car while you use the iffy ones to drive around in

).
Think of it as an on-going work of art..plus you can learn a whole lot of new skills getting the ute up to scratch, like welding & painting, if you have petrol-headed mates (and let's face it, who on this forum does'nt?

) you can ask for a hand or practical how-to's off them, but try to do as much as you can as it's a great feeling of pride in one's own work learning to 'do-it-yourself'.
Looking at the photo's of the ute..it looks like the drivers side rear quarter-panel has the worst rust located down low between the sill & the door (my guess this was rusty before the paint was applied and was rust converted & bogged over without it being cut out). Firstly...
DON'T PANIC..(I too have a spot on my rear 1/4 that needs attention soon

).. first with a wire brush attachment or flapper disc on the handy angle grinder remove a large area around the rust until you get nothing but clean steel showing then all you need to do is cut out the offending area a good inch (2.5 cm) around
the rust hole (make sure you cut out
all the rust here if it runs up or back attack this too!) once you have a neat & clean hole in the side of the car get out a bit of cardboard or paper and make a template of the hole, one you've done this cut the template out and check it to make sure the it fits into the hole perfectly (if you make a mistake here just get another bit of cardboard), once this is done draw the shape on the new steel sheet (which you've picked up at the local steel suppliers..
forgot that little bit of information..did'nt I

you can get off cuts from them for a few bucks if you don't wanna buy a whole sheet)...now cut the sheet out (inside the line) to the shape..this area of the car has a slight bow in it so make sure you
lightly bend the sheet to shape...once ready all you have to do is hold the new piece up to the hole and check that it will fit a perfectly as possible (if any bit overlaps grind or file it down until it fits..you also don't want to have a big gap anywhere as it will become a pain when welding it in! If so you can cut a small bit and weld it to it before it's on the car...that's why we check the new piece BEFORE we weld it in!!!!!).
Now all you (or a competent mate) have to do is tack the new steel into position...at this point I weld it in in small runs as not to warp the panel by having it get too hot...some blokes are genius' & can do it in one go...not me!

Once it's all welded grind down the weld until it's the same height of the panel then etch prime, bog (if needed) prime then paint & there you have one bit repaired!!
Now
that's one piece you've done yourself..keep this up and the old ute will get better & better.
It's the way my car is done and I love the thing...the more bit's you do the better you get & the better the ute gets
NOTE: if you plan to do the whole quarter panel remove all the paint from the door to the seam that runs down the center of the tail light & where the roof & sill joins.
Have fun

CRICKEYS....I'M turning into Rosco!!!
Scotty