The PPL and FRTOL are two entirely seperate licences with seperate application forms. You do not have to apply for the radio licence with your PPL.
The drawback is that you will be very limited where you can fly as you will not be entitled to use the aircraft radio without a FRTOL; unless you carry a pasenger who has a FRTOL. If you took the communications written exam more than a year ago you will have to take it again as its validity is only 12 months for a stand alone FRTOL.