Before you can start an intensive course you need to get a provisional driving licence. You are not aloud to drive on the public highway without a provisional licence. Your provisional licence is valid from the date of issue or your 17th birthday, whichever is later.
Application forms are available at Main Post Offices for the provisional licence. You can also apply online here providing you meet certain requirements.
Once you have got your licence you can apply for your theory test. You can do your theory test before you start your lessons or intensive course. Some crash courses include the theory test, some do not. You will need to ask the driving school offering the intensive course.
At the end of a succesful practical driving test, the examiner will usually offer to retain and then destroy your provisional licence and you will automatically be sent your full driving licence. You do not need to wait till the licence arrives before you drive - your pass certificate is acceptable proof.