Your vehicle will want to roll back. To avoid this you must use the accelerator, clutch and parking brake together.
Much of the drill for moving off uphill is the same as for moving off on the level.
Driving - The essential skills pg 99
This requires good timing. If you release the parking brake too soon, the vehicle will roll back.
The vehicle will stall if:
Practise the steps until you've mastered the technique. Then practise moving off uphill without rolling backwards; from behind a parked vehicle and at an angle.
The more you practise this manoeuvre, the more competent you'll be at getting it right.
Driving - The essential skills pg 100
The routine is simpler than moving off uphill because the weight of the vehicle helps you to move away.
The aim is to prevent the vehicle from rolling forward down the hill whilst moving away. The most effective, and possibly simplest, method is as follows.
However, there may be other methods that can be employed. If they ensure that the manoeuvre is carried out under control, they are equally acceptable.
Driving - The essential skills - pg 101
Parking on hills. If you park on a hill you should