PC Specialist don't have anything worth buying in that budget.
For £800 you'd want a GTX 1050 ti minimum.
There are laptops you can buy from PCS in that budget range, but I wouldn't recommend them for gaming.
Does it need to be a laptop? Desktops tend to offer more performance per £, and you can upgrade individual components, whereas to upgrade a GPU or CPU in a laptop you need to buy a whole new laptop.