Well people, after much searching and trying various bulbs & Led's, I have managed to source some 'plug & play led's totalling the grand sum of £2.31 delivered. The company to get the correct LED's from are called Crazy Leds
http://www.crazyleds.co.uk/ and the part number for them is T5/286 2XPLCC-21 and specify you need green. They take paypal so its easy and mine were delivered next day.
The job is very straight forward and takes around 20-30 mins and I have attached some pics below.
1 remove left and right hand infill panels and then the screen.
2 with ignition off, unplug the multiplug from the back of the clocks (push the tab down and pull)
3 undo 3 x 10mm nuts securing the clocks to the frame, one at the top and one either side.
4 remove the complete clock assemby from the rubber mounts
5 remove the rubber strips (if you have them) and the 7 x phillips screws from the back of the clocks
6 twist anticlockwise the 2 outer bulb holders below the green indicator glass.
7 pull the bulbs from the holders and insert the LED's in their place
8 put the bulb holders back in and twist clockwise to lock
NOTE LED's will only work one way round so before you put the back of the clocks back on, plug it in and try the indicators. If the green lights dont work, turn the LED'S round and try again.
9 Once they both work, turn off ignition unplug and replace the back of the clocks.
10 put clocks back into rubber mounts, fit 3 x 10mm nuts & washers
11 replace screen & infil panels, Job done!!
1st Photo is standard bulbs, 2nd is Led's Fitted,