Got a horrible grinding noise from the left front wheel, when turning the wheel either way the sound will completely go, also when I brake the sound also goes its just when I'm driving straight and the faster I go the louder it becomes.

Braking is completely fine as well and pads are also fairly new so cant see it being that?

 

Went to peak district yesterday and were driving on some fairly rough rocky roads so Could something be lodged in the brakes causing it to grind? 

Yes, sounds like a stone got lodged between the disc and the guard plate.