So just an update on this. Got the mot with the original bonnet
I have since bought the w205 bonnet from a breakers for £50 it had a pretty big dent in it but I didn't want to buy a nice one just incase I couldn't make it work. I managed to somewhat straighten out the dent but the w205 bonnet is aluminum so this was pretty difficult and time consuming.
I then made a rough template of the old bonnet out of card. Then used this to cut the shape of the new one, basically just trimming the edges and increasing the radius of the curve where the bonnet meets the windshield.
This meant I could fit the bonnet in the right place so I then tried to make the hinge mounting points for the new bonnet. Again this was very difficult as I couldn't weld to aluminum. I ended up bending the original mounting points down so that they would fit.
I then attached the ball for the gas struts this is where it gets a little sketchy. I had to rivet this on as I couldn't attach it to the aluminum any other way without damaging to outer skin of the bonnet.
I then used the existing threaded holes for w205 bonnet latches to mount an extended plate for the w203 latches, which I then reinforced with rivets. Then for the secondary bonnet catch I cut an access hole in the inner skin of the bonnet and drilled holes to bolt up the secondary latch and tightened using the access hole. I also had to raise the point on the car that this secondary catch catches on. The bonnet was FINALLY fully attached!
There was still a large gap between the inner and outer skin of the bonnet due to the trimming on the edges and by the windscreen ideally I would have used a bead roller or a seam roller to attach the 2 skins together. I didn't have either so I bought some silicone seam sealer and hoped it would hold. I ran this down both edges and round where the windscreen is unbelievable it seems to hold. However instead of pulling the inner skin up it pulled the outer skin down this means that there is a considerable lip between the bonnet and the wing which I am stuck with now
Finally made holes in the bonnet for the screen wash jets and bought universal nozzles to fit the holes.