Unfortunately F in a CRJ is pretty much the same as Y in a CRJ, except the seating configuration is 1-2 rather than 2-2. I wouldn't waste the Avios. You are unlikely to get any decent food or drinks on a short hop, so not worth it from that standpoint either. I have been on RJ flights three hours long where no food at all except for half-ounce packets of pretzels was served in F.