Update>>>> Today I performed the strip down, here are a few pointers for anyone else doing this.
1) the video clip is spot on, but I could only get the wiper blade puller on with arms in the up position, hence stop wipers with ignition when facing directly up, and mark blade on screen with masking tape, this so you know where to put them back.
2) one came off ok, other fought back, but I won !!!, remember to use a smear of copper ease when you put them back on.
3) the plastics are a bit fiddly, but can be done without putting bonnet on high bit, I found if you release passenger side first, the other side comes out ok.
I suspect this car has had a new screen in the past, one of the plastic retaining tabs on the top plastic was already broken, and I found a 10mm socket and spanner in the tray (now added to all the others I have). To say it was mucky in there would be an understatement, you could have grown plants in the muck, in fact there was something growing !. The "drain" that Dec pointed out is on both sides, however, all it does is drain to the tray underneath, the actual scuttle drain is about 30mm by 20 mm and drains into the inner wing both sides, no blockage (dam), so I cleaned it all out, after removing wiper linkage, and made it all clean.
I then took off the right hand wheel arch liner, where the cars with a sun roof have their drain, is a hole, filled with a rubber bung, you cannot see this unless the wing is taken off, however, I could feel it, its right under where water drains from the scuttle, so I used some sealant and smeared it as best I could round the bung, just in case that is the source of my leak, only time will tell now.
Due to suspecting a screen has been fitted, my next task is to check and seal the top, just in case some water is finding its way down and into the car.
For now, that's it, thanks for all the help and suggestions, the wiper blade removal tool was a godsend.