You mention you are selling up, but will you have an address in the UK? This can be friends or relatives, but you usually need somewhere for banks to send statements, or you could find yourself cut off from funds. When you state being away for a year does this mean no return trips to the UK at all? Also are you going to work, and if so you need to consider the tax implications. If you are away for more than a financial year you can avoid UK tax. If you have a 'pot' from selling up, then consider an offshore bank account for keeping it. Get an accountant, the fees are worthwhile in not having the Inland Revenue hounding you when you return. You also need to check that your insurance cover will allow you to stay away for a year, some Companies are better than others for this. Also do not stay in any one country for more than 180 days total in any year, or you will be classed as resident and taxed on your worldly income. Most European countries run the tax year from January 1st to the 31st December.
On a practical note, check sites that are open in the winter. The ones in Spain usually are but can get quite busy with all the 'oldies' seeking winter sun. You also need to have winter as well as summer clothes so watch the load factors, especially if you take books and other hobbies etc. You may also want to look at getting a local mobile telephone SIM card as this will make your calls cheaper.
http://www.0044.co.uk/france.htm
may be of help.
Remember to keep the car taxed, or you may be stopped in France for instance. Although technically it is not required in France, not having it will lead to suspicion from the plods that you are up to no good.
Have fun whatever you do and enjoy the time away.