Commercially,I have used radio ststems and the cables to or from the control panel must be wired in fireproof.This includes links to communications,power supplies and auxillary outputs.
With regards to the L2 classification,this would indicate that they are referring to an installation to BS 5839-1:2002 which would be a zoned control panel (wireless or not) amongst other things.An LD2 system relates to BS5839-6:2002,which covers systems for dwellings, and within this there are specified grades of system (A - F).A grade A is your actual 24 volt,control panel,power supply normal fire alarm and F is battery smokes.
Read section 21 of Part 6 which relates to radio systems in dwellings.You can use radio for grades D & E and F but (at risk of sounding as if I'm repeating myself) the fact that they have asked for 3 zones and an L2 sytstem means they would at leat want a control panel that the detectors report back to.It must have a visual indication also.