Useful links:
Cars for Learner Drivers
Which car should I use to learn to drive?
If you are going to augment your professional lessons with practice in a car belonging to members of your family, then I would advise looking for a local instructor who has a good reputation and operates the same make of car. Don't be too ambitious and want to drive powerful cars until you have quite a bit of post test experience and undertaken some Pass Plus lessons or an Advanced Driving Course or both.