You need a charge regulator.
I use a 12v lead acid leisure battery for camping with a solar panel to keep it charged.
We get all of our lighting and charging of phones and mp3 players of this even in the UK.
The controller cost me about £30.00 it was worth it.
You connect the battery to one set of terminals.
The solar panel to the next and the load to the next set of terminals.
Handles all the charging and load for you.
Something like this:http://www.maplin.co.uk/charge-controllers-97384?ordercode=L22BR
You will have to pick one to match your battery and panel.