Do you know much about electrics? Have a multimeter? An RF one does need wired in to the boiler. Its the thermostat that send a signal to the receiver which in turn sends a signal to the boiler to fire through a cable.
My recommendation is to get an engineer out to wire it up. Saves you any grief or possible electric shock. lol.
Should cost you an hours labour plus materials.
You know then the work will be covered by their own warranty on the installation (Mine is 12 Months) of the stat. You will get the right one and it has been installed correctly.
Surely that alone, never mind any potential headaches, is worth an hours labour to a competent local engineer. They would appreciate the support as it is tough out there and if you like them then they could be invaluable to you in the winter when your boiler goes down.