Hi, makes no difference you don’t have an existing stat. Very simple to do, two choices: one is to have a wire run from the boiler to the place you would like the thermostat. Or the second option which would involve less disruption would be to have a wireless one installed which would involve having a receiver wired into the boiler and then a battery or power operated thermostat wherever you like. I would highly recommend the Nest Learning Thermostat. They are a little bit dearer but really good units and potential to save money.
It's a pretty simple job. You can either use a wired stat which will require a cable from heating system to stat location or a wire free. This will be slightly more expensive but will restrict any disruption.