Starting out in rocketry.
The best advice for someone brand new to the hobby is to join the UKRA (United Kingdom Rocketry Association), by being a member you get insurance to fly your rockets, and access to there website and online forum. They also include a Model rocket kit in their new member’s packs. The next step is to build a model rocket and fly it at a local club launch first; it is best to get some experience whilst Building your model rocket. It isn't difficult or expensive and it gives you an insight into what construction methods are used when building rockets and how all the components come together and work. You can buy additional model rocket kits made by Estes and Quest from most hobby shops or see some of the vendors in the links page of this site.
The next step after you have built some model rockets is to get involved with a rocketry club. (Again see the links page of this site. To find a club close to you). This is because of the logistics involved in flying the larger rockets some of which can travel several thousands of feet into the air, and club launches are mandatory for more advanced rocketry. Not to mention the wealth of information and help you will get from talking to other rocket flyers at the launch meetings.
There is also a large number of rocketry websites, which offer advice on anything rocketry related you could think of. Again a lot of these sites can be found on the links page.
A link to my how to build a High Power rocket series.