I've ordered a new desktop which will be made of solid oak. Its dimensions are 2300mm (L) x 820mm (W) (approx. 90.5" x 32"). I doubt it's relevant except for estimating its weight but it's 27mm (1") thick).
The long edge of the desk and one of the short edges will be against masonry walls (i.e. it'll be in a corner). For clarity, here's a diagram:
Ideally I want to mount it to the wall using brackets rather than legs. I'm thinking of using two (at 767mm and 1533mm) or three (at 575mm, 1150mm and 1725mm) long brackets from the back wall. I've been looking at the brackets here.
My question is what length of bracket would I need (the ones I've linked to go up to 680mm in length) and would 3 be overkill (they're rated for 150Kg per pair)? The desk will hold three or four large computer monitors and I want to know I can lean on it without worrying!