Choosing The Right Thermostat For A Zoned System

In the process of completing a new heating system in our house. We have a three storey house, with an extra garden room and rooms on the half landings. There is UFH in half of the kitchen diner, the garden room and the downstairs small shower room. We have a further 13 rads spread around the four bedroomed house. We have a Worcester-Bosch 30 Cdi Classic system boiler and a megaflo. The question is this. I wanted to install a Nest thermostat. I have been recommended though to set up a zoned system. I was told to install a Heatmiser system with 6 seperate thermostats (one for each room with UFH) and the rest for the other parts of the house I guess, as well as a timer for the megaflo. As far as I can see, the system has not been developed for zoning other than the UFH. I was told that the Nest will not be as efficient as the Heatmiser as it reads the ambient temperature where as the Heatmiser will be reading the floor temp. My question is this. A/ Do i need a zoned system for each room? b/ Can I run a semi zoned system with two or possibly three Nests (one for upstairs, one for the areas with UFH), c/ If not is the Heatmiser good and do i really need 6 units? Is there another system which would be better. 

Thank you for your help with this. 

Of course you need a zoned system. With no zone controls, just what do you expect the thermostat to control?

thermostatic valves on each radiator is the most cost effective solution if you don't want to modify the plumbing.