The FRTOL is issued FREE of CHARGE to holders of any other UK issued flight crew licence. Thats why the application form contains a section for details of that licence.
It is also issued FOC to persons training for a UK licence, again there is a section for the details. So as long as you have a valid medical certificate you can get a free FRTOL using FCL508 SRG 1106.
http://www.caa.co.uk/docs/33/SRG1106FF.pdf Read the notes on the back!