We have been doing this, but from Portugal for the last few years. The site we use is very secure and we leave our car on the site as well. i would suggest you try for a discount for the time you are away - you never know.
We use Ryanair and we have had no problems with them, abide by their rules and its all OK.
The first time we did it, we flew home at the end of November and then back mid January. We were amazed at how cheap the flights were, they have gone up a bit since then though.