You seem to be stuck between a rock and a hard place!
The FI course is the best option to gain more hours & experience, no doubt about it. You will find work some where in the country as an FI (R),it wont pay well but will get you the hours you need to go commercial. Theres a school in Fife looking for an FI (R) at moment, to do weekend work.
However, if you dont have the money for the course!
I'm not sure i know anyone who is flying commercialy, who didnt have to do the FI rating first, to hour build their way to a commercial job.
Commercial work will be nigh on impossible to find with 300 hrs, i know, i've been there!
Lets know if you get on the GAPAN FI scholarship.
Best of luck
H-J