2001 Vauxhall Vectra loss of water

I noticed that i had no heating but my temperature gauge would go through the roof so i changed my thermostat but still no heating and temp gauge is too high i am also losing water from my expansion bottle but my oil is fine and i dont have white smoke coming out of my exhaust, i have put at least 10 litres of water in my water bottle and there is no water underneath the car when the bottle empties