yeah basically is doddle, its just access is a pain.
Just pop off the 6 plugs that go onto the DIS, some can be a little stiff, but keep wiggling and they will pop off.
Basically if you imagine a giant lego block, bolted on the back of the engine!
Just remembered, the DIS packs are not all the same. Some are bolted on at an angle, some straight on i think.
Don't pay anything for the DIS if you can avoid it really, its just a usefull reference. Taking it off was easy enough, putting it on was slightly harder, looking at one in front of me helped me to see what I was feeling.
There are basically 4 nuts in each corner that you need to un-do, i used one of the halfords small socket sets to remove them. Apart from the easy one which you can see the others are a b!tch really to un-do, often the movement to undo would be so small. 1 nut took me about 10 mins to undo cause it could only move the socket arm 1 click at a time, so took a while.
You might need to bribe the Mrs with something