The 'small' socket is a DIN 16A unit, much better than a cigar type.
The DIN 16A unit fits perfectly into the area behind the indicators, there is a flat surface and the wires all sit inside the panel (the one the indicators are fixed to), and it's easy to remove too.
The 16A connectors are different, but what I (and many others) do is to use a single 16A connector fitted to a multiway cigar type, so you can charge your phone/satnat or run your heated clothing etc from.
Here is a link to one ->
http://www.ebay.co.uk/itm/12v-Din-Ac...item19be6a2984
You can buy these as complete socket / plug kits in Halfords too (or Maplin, RS, etc)
As for wiring it in.... you could wire it directly to the battery, but best to have a relay fitted that connects to the lighting circuit thus: ->
Don't take too much notice of the wire colours, just for reference (and you'l rarely get two people agreeing which colour should be which) - you can use all the same wire (just label it well)
It's easier than it looks.