We bought a yacht in Greece 5 years ago & have been sailing the eastern Med. ever since.
You ask about sailing back to the UK Why would you want to do this?
If you plan to sail in the summer months and return to UK in the winter,there are plenty of places to leave the boat safely.
Buying can be easy.the place is awash with boats for sale,this is partly because the economic situation has priced many people out of owning a boat.Greece is now an expensive country to sail in,compared to a few years ago.
You need to have a good budget if you want to have a decent standard of living,Food,drinks fuel and services all add up.
Having said all that ,it is still a wonderful place to sail.
I would suggest that you charter for a couple of weeks first,to get the feel of the area,the Ionian has plenty of charter boats available .