1. Disconnect the battery.
2. Under the bonnet there is a rubber trim which must be removed where the bulkhead meets the scuttle panel. The rubber trim is held in place by plastic clips that go through the scuttle panel, through the bulkhead and then through the bottom of the rubber trim.
Picture of the clips for reference:
To remove the clips, gently tease a small flat headed screw driver under them, and work them upwards. Once there is enough clip sticking out to get a grip on, pull them out by hand.
Here you can see the hole in the plastic scuttle panel, bulkhead and rubber trim that the clip goes through:
Remove the clips all the way across:
3. Remove the wiper arms with a 14mm socket:
Now we remove the scuttle panel, its literally clipped in all the way across, no tools needed here. Starting from the bottom corners of the scuttle panel, gently pull it up. Then starting from on side to the other, pull the scuttle up and unclip it all the way across the top.
Here you can see the scuttle panel unclipped:
You can now remove the scuttle panel, lifting it upwards towards the top of the windscreen. Don't scratch your windscreen!
Scuttle panel now removed:
Here, on the drivers side we can see the windscreen wiper motor and mechanism:
4. Time to remove the wiper motor and mechanism, it all comes out in one piece.
Unplug the plug going into the wiper motor, then remove this bolt with a 10mm socket:
Then remove these two 10mm bolts on the right hand side of the mechanism:
On the left side the unit slides onto a locator shown here:
Simply slide the whole mechanism to the right then lift out of the car.
The wiper motor and mechanism removed:
5. To remove the wiper motor from the the mechanism, flip it over and you will see an arm attached to the back off the motor by a 12mm nut:
IMPORTANT! Take note off the position, of the arm in this pic. The arm must be re-attached in roughly this position, incorrect position can mean your wipers will swipe down instead of up!
Remove the 12mm nut and washer, the arm is still attached on a spline. Put a large flathead screw driver down the back of the arm and give it a gentle tap with a hammer to release the arm.
Then remove the 3 bolts around it, using a 10mm socket, spray them with a bit of WD40 first. The motor will now come away from the mechanism:
(Notice one bolt snapped on mine).
Give the mechanism a good wire brush and clean, clean all the gunk out of the joints and re-apply new grease to them. Installing the new wiper motor is just a reversal of removal - MAKE SURE THE ARM ON THE BACK OF THE MOTOR IS RE-INSTALLED IN THE CORRECT POSITION.
All back together and cleaned up:
6. Install the wiper motor and mechanism back into the car with the 3 10mm bolts and re-connect the plug.
BEFORE RE-INSTALLING SCUTTLE PANEL AND TRIM, RE-FIT YOUR WIPERS AND TEST THEM TO MAKE SURE THEY ARE WORKING!
Remove wiper arms. Align scuttle panel up and clip it back into place working from one side to the other.
Refit the rubber trim across the bulkhead making sure all the clips go through the plastic scuttle panel, bulkhead and rubber trim.
NOTE: When refitting the rubber trim, all the holes are elongated APART from the middle one, when refitting the clips put the middle one if first.
Re-fit wiper arms and re-connect the battery.
7. Grab a beer!
I can't think how you know the parts highlighted in red are so important, Rob... 
