Slightly off-topic, but I'm looking for a cheap soldering iron (<£25) that would be good for getting me started with basic DIY audio. Of course, lower wattage ones will be cooler and therefore easier to work with for small PCBs etc, but are there any downsides to something like this? I wouldn't be doing much more than PCB/veroboard work, and a small tip might be a nice feature. What is the best tip shape for this stuff?
The best tip shape is a chisel point that fits the parts you're working with. The narrow conical points are, IME, mostly worthless. They lack sufficient thermal mass to transfer heat effectively, and force you to stay on a solder joint far too long. (The only exception I've found is with Metcal irons, but they are extremely expensive and operate on a different principle than regular irons.) The Hakko 936 (or clone thereof) is a good basic iron, although more than your budget allows.
The one GoldiLocks linked to looks like an adequate iron, you really want to be able to vary the tip temp, as well as have the option of different sized tips.