Hi Joolz,
Enjoy Plakias, it's a wonderful place. As for cycling, based on the experience of my other half Sue and I, it can be really good fun to hire cycles for a few days.
We've hired from the shop on the road down towards the sea front nr the doctor's, close to the new Post Office (we always stop in Stella's just up the road from there, which we can thoroughly recommend re quality and price).
The coastal routes are fairly flat, although the hills can understandably get a bit steep. Only tip is just to remember which way is up and down re gear changing as Sue got it wrong last time and ground to an ignominious halt on the short climb west out of the town!).
All the best
Graham