So, as there are little bits of surface rust poking at the bottom of my tailgate, and some surface rust around the handle. I decided to get rid of the rust and try my hand with some filler...
I quickly proceeded and found this under the handle (after an ickle bit of sanding):

as you can see, its not too awful...
Then I thought, hmm, I'll take off the number plate, maybe its got a little bit there, and I found this staring back at me!!

So. my boot at the moment is this:

Its gone from an easyish bit of surface rust, to a gaping hole, so how could I get this sorted?