Andy, you have a PM
In Hometronic land for a single zone system you would need a Manager and power supply, Room Sensor, Boiler Relay and a Web Manager. While the R4 manual is useful it is a few years old and many of the modules have been updated since and some new modules are not listed at all! You will not find any mention of the Web Manager, this is a brand new piece of kit from Sensible Heat as Honeywell do not have any native network-capable modules for Hometronic. The new Web Manager allows all of the user functions to be carried out using any suitable browser-based device and would be the only part of the system that needed to be next to your router assuming you don't want to use powerline networking products to bridge between 2 locations.
So Hometronic can meet your needs and requirements (specifically as it uses wirless comms) but it does not come cheap. It would not cost a huge amount more to zone your heating (using the Radiator Controllers) and have much better control and this would also make better use of the capabilities of the Hometronic package.
As I mention in my PM there are no other wireless stat systems I'm aware of that have ethernet networking/webservers built-in. There are some wired systems that operate over a comms bus and have software to allow central control from a PC but ths means running cables & therefore some disruption to install.