Widening french doors

[britishboy7]

We currently have french doors (1.3m wide opening) leading to the outside in a single story extension to our lounge, We'd like to open it up by another 1m, and probably fit sliding doors. The doors we've seen will be approx £1800, do you have any idea on labour and whats involved?

I'm guessing it will include:
propping up existing ceiling in extension (nothing above it only a sloped, tiled roof)
removing doors and cutting brickwork back/widening gap
fitting larger lintel

Also, would I need permission to get this done?

Is this a big job? Am just trying to cost it up and see if its viable, I'm in the South East if it helps