Just to confirm some of the info that Razor & Vansmith have given you, you will need a Mac
with an intel processor, with at least 2GB of Ram, but 4GB would be more suitable.
The Mac laptops are great, but are very expensive in the UK, also they have small screens,
which can be a problem when you start doing programming with the Xcode develper tools,
which you will be using for app development on your mac.
The best choice would be a 21.5 inch iMac.
iMac - Desktop iMac Computer - Apple Store (UK)
But you might want to consider a Mac Mini if your on a tight budget.
The New Mac mini - Now With OS X Lion - Apple Store (UK)
The mac mini can be used with a TV with a HDMI connection, which you might already have in your bedroom, but you will have to get the keyboard and mouse as they dont come
with the Mac Mini as standard.
I have had a look on the UK eBay site for you, and have seen both of the above systems
for half the new price, but make sure you buy one thats no more than two years old, also try and buy from somewhere local to you, so you can pick it up in person, and check it is
working correctly, the chances are if you buy local and private, the seller will have upgraded
there system, and will be more likly to want to help you with advise.
After buying a Mac, you will want to donwnload the Xcode developer tools from the Mac
App store, these are free to download, and the newest version is 4.3.
https://developer.apple.com/xcode/
With this version of the Xcode tools you can make apps for iOS versions 4.3, 5.0, and the
new 5.1 which will be released some time this summer.
Also you can use it to develop Mac apps for versions OSX Snow Leopard, Lion, and
Moutain Lion which will also be released some time this summer.
All of the above equipment and software will be required for you to get going.
As for learning, if you have not done any coding before, you want to learn a little ANSI C,
and then Objective C, and one of the best beginner books is this one.
http://www.amazon.co.uk/Objective-C-Programming-Ranch-Guide-Guides/dp/0321706285/ref=pd_sim_b_1/277-4360122-6457649
I can highly recommend this book to you, it is written by some of the most experienced
Objective C tutors, who run acclaimed coarses on Mac and iOS programming.
You wont find it easy if you have no experience of coding, but take your time, and dont give
up when things dont make sense, just take a break and try again.
After completing this book, and having fully understood its content, then you might look into
getting this book.
iOS Programming: The Big Nerd Ranch Guide Big Nerd Ranch Guides: Amazon.co.uk: Joe Conway, Aaron Hillegass: Books
This book is also a great learning tool, but will only make sense if you understood the
basics in the first book, so dont rush, it only gets tougher if you do.
Also once you start studying, come back and visit forums like this one and MacRumors, as
you will find experienced programmers that will try to help you out, but we cant promise to
always have the awnsers for you.
My advise when posting questions is to be clear and specific, dont post dozens of lines of code, as most of
us dont want to spend an hour reading these lines, and then an hour debugging them in the
debugger of Xcode, so post only the lines of code that are causing issues.
Hope this is of some help.
Regards Mark