ARGH WHY?!?

[Mux213]

Jezza,

I could be dead wrong but to me it looks like someone welded a plate on the outside that you can see through the holes left by rust probably as a way to repair the rust damage. Its not a nice solution but it works, unless if there are issues we can't see on the above picture this will probably get through MOT.

But if you want it nice they should cut out the bad part and weld a new plate in. Also I am not sure what this does to the strenght of your car..

Get us some more pics man so we can see what is going on.

As for jacking your car up, troublesome if it hangs so low. You have a couple of options (besides going to a garage and putting her on a lift).
With a good jack you should be able to jack your car up by putting the jack in the middle of the rear axle and lifting the rear axle off of the ground, then when there is enough room use jack stands to rest the car on.
The other is to get some of those things you can just drive your car onto.