timegoesby wrote:
If I install a ground floor veranda on the garden side of the house,
with the roof of the veranda being the same as the main house roof
tiles, uprights supporting the veranda roof, a rail and fully open all
around, as you see in houses in hot countries, will I need planning
permission?

Could I build it to a level that all I need do in the future is istall
glass doors and windows all around, insulate under the tiles in the
small area under the veranda roof, and then have an extension room?
Depends on the size and if you already have anything eating into your
"permitted development" allowance.
Why not ask your local authority? You will need to conform to building regs
anyway.