Quick question do I need to use both wall plates as my 40" will comfortably sit on one? Instructions here. http://www.bracketsrus.co.uk/images/manuals/G01.pdf
Depends on the wall you're mounting it to and the weight of the panel. If it's a heavy panel and/or you're mounting it to a stud wall, yes use both plates and split the load between them. If it's light or a brick wall, then you'll probably be fine.
Was going to also suggest anchor bolts as I used some on a punch bag once but manual says you got some with it. If you think it's going to play on your mind after, use both
I actually think that the single plate is more than enough especially with the size of the anchor bolts supplied. But for peace of mind and I suspect I might get a bigger TV in the future I will install both plates. Thanks to both of you.
Depending on the quality of brick, you might have better luck with chemical anchors (e.g. Anchorset + studs) than anchor bolts. Super-easy to use and holds excellently.