Body corrosion

I have got a 1998 Discovery tdi with a lot of patches of corrosion on the body,especially on the wheel arches.
How do i treat it,and do i need to treat up behind the wheel arches.
Also the wheels are corroding too,and need treating as soon as i can.
Chris

im in auto collision right now. 
 
if its just rust bubbles you just take lets say a 40 grit sandpaper and sand all the rust off about 3 inches past the corrosion area.  then use a 3m brand body filler if needed.  prime and paint.  do not mask around the area for priming.  it makes hardlines which make for hard sanding when you paint it.
 
this is the only correct way to fix rust without making it worse.

Thanks for your help,Do I need an Etch Primer on Alluminium panels?
Chris