1) Purchase the "Driving Test Success - all Tests" DVD-ROM for revision material ready for the Theory & Hazard Perception tests. you may also want to consider a few extra books to go with it, such as "Pass your driving test" by BSM to tell you how to do the basics like pull away + "Advanced Driving" by John Lyon to learn a few extra things other than the basics.
You may want to consider getting these now in advance, as apparently there's about 3500 rules & Regulations that affect drivers on UK roads, and you need a good knowledge of them to get through your tests, so it's probably best to get a head start learning it all. Also the practise for the "Hazard Perception Test" (taken at same time as the theory) done on the DVD-ROM I recommended takes a while for you to settle down and make the transition from being over alert like a startled meercat and clicking on too many things, to cooly being able to filter out stuff so you only click on the ones that matter.
2) Apply for your provisional licence a few weeks before your 17th Birthday so you get it on time - you'll need £50 for this.
3) Book lessons with someone such as "Bill Plant Driving School", "AA Driving School", "BSM Driving School", etc or a decent local independent driving instructor I've been using a bloke from "Bill Plant Driving School"... first lesson free, then 5 lessons for £56... £22 a lesson after that
4) After a few lessons, book & take your theory test... that'll set you back about £31 https://www.gov.uk/book-a-driving-theory-test
5) Continue taking lessons until your instructor tells you you're driving well enough to take the practical test.
6) Book the Practical test... it'll set you back about £60 - £70 a go, so definately don't take it before you're ready 'cos you surely don't wanna screw it up too many times at that price.
7) Take the practical test
8) If you pass the practical test, you can trade in your provisional licence for a full licence.