Outer Limits 4x4 Board

This may be a stupid question, but what (in simple terms please) would cause my steering to only slightly pull to the left whilst driving, then when braking pull harder, not uncontrolable though, just anoying

Tyre pressures, wheel alignment......maybe.

Brake Calipers, brake pads...possibly

Steering Balljoints...condition??...might be

Or the road, slightly slants off to the left for water run off....unless you're driving on the right or the wrong, or the left side backwards ...

As Mandy says, there a lot of things that can cause it. My Rangie used to pull very hard to the right under braking.
I replaced the A-frame bushes and ball joint last week and now it is a lot better. I think the worn bushes compounded a small braking problem because the worn bushes causes it to steer from the rear wheels.

With the rear axle, it is usually worn trailing arm bushings as the rear axle then steers the vehicle especially when braking.

Anyway, as stated. Make sure the tyre pressures are even. Check for warn out bushing and check the alignment.

all the things previously mentioned above, but first swap your front tyres left to right and see if that changes anything. If not probarly a simple toe adjustment or new set of brake pads.