What exactly would I need for this? I've found what look to be the right kind of sockets in Maplins but does anyone know what wiring I'd need and where to get it from? Is it possible to get a passthrough connector so that it's just plug and play, pretty much?

Wire it into the 12V power circuit in parallel configuration. You should consider adding an extra fuse for your additional socket as well.

Not sure what you're planning to do but wouldn't something like this be a whole lot easier, or am I way off the mark?

cigarette socket 2-way splitter

Well I've got a griffin itrip auto pilot which has playback controls on the bit that goes into the power socket and I just wanted another socket, preferably out of the way to plug the satnav into when I'm using it.

I'm just worried, with using a multi socket device that it will either get in the way of the handbrake or be a bit unstable. The one you suggested looks pretty compact though, and it's cheap so I'm gonna get it and give it a go. If it doesn't work out, I'll be back!

Well in that case, take a look at the other options that are available.

Here's a link to the search I used.

splitter search link

Well in that case, take a look at the other options that are available.

Here's a link to the search I used.

splitter search link

I did a similar search and most of them are huge or are on long cables. I'm trying to keep the ipod controls in as near to the original socket as possible because my hand can fall there naturally when I want to change songs. The Satnav, well i guess it doesn't matter too much, as long as it doesn't get in the way.