Hi Hans and welcome
I havent stayed in the Greenworld but I have stayed in the apartments next to there, Julian Forest twice now and returning there in June for 3 weeks. It is lovely and peaceful there and the pool etc looks wonderful. Like Alan says, there is a regular dolmus to take you into town, but if you wanted to walk you could do, but I reckon it would take about 30 minutes especially when its hot! Dont think you will be disappointed.
Tania