Probably the easiest way to get into electronics as a hobby is to build a kit. There is a large range of kits available, some of which are only suitable for more experienced constructors. It's important to start with something fairly straightforward, after all, if you can't get it to work when built it might put you off electronics completely! But first a word of warning:
That said, if you'd prefer not to use batteries, most projects can be powered through a commercially built low voltage mains adapter. Dire warnings over, let's continue. Maplin have some kits, however their range has been vastly reduced recently. If you have a Maplin store nearby you might like to browse their selection. A much wider range is available from Quasar Electronics (contact them for a catalogue, although the full range is on their web site).
Your choice of kit depends on what takes your fancy, but don't choose anything too complicated. It's best to choose a project that will operate on it's own without needing to be connected to another piece of equipment. I would also urge beginners not to choose audio projects, as these can be more difficult to get working properly, and fault-finding can be tricky without the right equipment.
Good beginners kits to choose from Quasar include 'Running Light Effect' (1026), 'Stairway to Heaven Game' (3005) and 'LED Dice with Slowdown' (3003), shown below in order (click each picture for kit details). Quasar's web site includes suggestions for suitable enclosures and power supplies where appropriate. Many other kits would be equally suitable.
If you choose an automotive project you will need some basic knowledge of car electrics to install it in a vehicle. Personally, I would recommend the 'Running Light Effect', as it is suitably impressive, and immediately obvious whether it works or not.
Some kits are based around a microcontroller, which allows a complex project to be built with minimal circuitry. However if you want to understand how the circuit works I'd avoid microcontrollers at this stage, as 'real' circuitry is often easier to understand than a 'black box' controlled by programming, the function of which may not be fully explained in the kit's instructions, or source code may not be provided.
It's best to choose a good quality kit from a reputable source, not one from 'bargain list' supplies. As I have found the hard way, these may have been lying on a shelf for too long, and the components may have degraded - there's nothing more frustrating than a faulty kit!
Remember, the main emphasis at this stage is getting an easy-to-build project that will work, even if it doesn't do anything particularly earth-shattering when finished.
When you've chosen your project you'll need some tools to construct it with. The next page explains what you'll need.