Before you go off the deep end with wireless controls etc. (not that there's anything wrong with them), I'd step back a little.
At the moment, all you know is that you have two thermostats, and an old standard timer. I assume it is the old On/Off/Timed switch with a dial above it that allows 15min intervals.
It sounds like an abnormal setup, in that if you have two thermostats, then you would normally have a programmable control box for the zones that are controllled by the thermostats (from your post I infer that you know this).
So I wonder who put in the thermostats and why? (if they didn't put in a corresponding control box.)
One thought struck me, that the thermostats could be wired in series, i.e. if either setting is reached, then the heat turns off. Remember, all a thermostat is is an on/off switch that is operated by tempreture. I've never heard of it, but then again, I'm not a plumber (and maybe the person who put it in wasn't either
)
I also haven't heard of just a thermostat controlling a zone, it is normally the controller that does so (but I'm open to correction). I assume it is possible, if a bit odd.
So, if I was you, the first thing I would do is establish if you have the two zones. To do this you will have to find the exposed heating pipes, normally either in with the immersion tank, or in a cupboard near the boiler. By looking at how many valves you have you will get an indication of the number of circuits or zones. By how they are turned on/off (either a red lever or a mechanical/electrical valve) you will know if they are operated by hand or if a control was fitted which would normally lead back to the control box mentioned earlier.
Once you establish what you have, then you can plan a course of action depending on your starting point, cost, level of difficulty, value of gain you'll get (e.g. if it is small house with one zone currently, it may not be worth the effort to put in two zones - a couple of TRVs would be cheaper and almost as effective).
I don't want to suggest any course of action without getting more information on what you have.