Flights to EDI in October generally aren't as packed in Y as they are during the peak summer months. I used to live in Edinburgh, and flew transat from there on CO's EWR flight about once a month. You should not have any problems reserving window/aisle seats in the non-premium area of the cabin (Behind the Row 16 exit row, I believe), especially booking this far ahead. With any luck, you may even be able to score Row 16 on the 757 (reclining exit row with plenty of extra pitch and tray table in seatback, so arm-rests may retract. It's as close as you'll get to E+ on CO) if you can snag it at check-in the day of your flight. Enjoy your flight. Edinburgh is a truly amazing place.