Honeywell Evo could be used, either with two of the downstairs zones combined (sharing one time program but still using separate room sensors) or using two Evo Touch controllers, one for each floor, which then gives you scope to control the upstairs radiators indpendently.
That gives you class-leading levels of control for the room side heating,meat demand control of the heating circuits/boiler, plus hot water control too (if the boiler is not a combi).