Can I safely hang a 17KG TV on a drywall in the UK?
Yes. Google tells me that model is compatible with VESA mounting.

For heavy screens, be sure to buy a mount that is rated sufficiently, and is attached to the structure of your wall. (So for drywall covered stud-framed walls, you'd want to be sure to attach to the structural wooden studs inside the wall, not just the gypsum wallboard.)

You can use a stud finder to help locate the studs within the wall.