You might want to consider going to Belize. Ambergris Caye: http://www.squidoo.com/caye-ambergris is relaxing, not overly touristy and has fabulous snorkeling. Spend part of your trip on the mainland for a few days to see the jungle and Mayan Ruins.
New Zealand has beautiful beaches, both black sand and white, even one where you can dig your own spa pool in the sand, as there are hot springs beneath it. It also has plenty of native rainforest to explore, and plenty of exotic volcanic activity. Of course, it's on the complete opposite side of the world to Europe and thus expensive to get to, but once you're there you can have a great time on a budget. The beaches, the forests, the bubbling mudpools and geysers - they're all free to see.
Well if you been in Italy and you like it, maybe you should visit Croatia. Its not expensive destination at all, and also you can explore there islands and so on. To come in Croatia from GB it would cost you like 80 euros or something. They have plenty of islands ( around 1000 ) some of then are rly intresting.
You don't have to travel that far for an exotic destination -- in most countries you can find beautiful ott-the-beaten-path places. I recommend the Belgian Ardennes, a lovely place any time of the year!
Maldives <3
Bora bora/tahiti is somewhere ive always wanted to go, they have bungalows built on water that you can rent and it just looks super fun. Beautiful beaches, probably a rainforest of sort around. Looks pretty expensive though.
Dream time beach
India is it.Side trip to Thailand or Burma if You have time.You gonna luv it.