Agreed with the above - to the effect that £200 isn't realistic for what you want.
Even if you can get Warzone to run on a laptop's integrated graphics, the experience will be very limited. There's a real chance you'd want to upgrade your hardware in the near future. But you can't upgrade laptops in that way, so you'd end up buying a new system. Which means you'd end up paying twice over.
You could consider the PS4 over the Xbox (if the PS4 exclusive titles interest you more).
And apparently you don't need the PS4 Plus subscription to play it.
(Gamesradar also claim you don't need Xbox Gold to play Warzone, though that's not what the store page says)