The shape and size of your new driveway will obviously be limited by how much space you have but you need to take account of any additional parking space you may require, planting areas you would like to keep and whether steps or footpaths are required.
You also need to allow for rain water run-off, drainage requirements and kerbs or edging.
Once you have resolved the practical issues you can start to consider the shape of the driveway, curved or straight? and the type, size and colours of the blocks.
Your block paving quote should list in detail all of the work which is to be carried out and perhaps that which is not.
Also, you should agree the layout and dimensions of your new driveway when your installer marks it out on the ground.