Thanks for the responses!
I did not have a custom recovery installed, I have now flashed (via Odin) Philz, but cannot boot into recovery. I hold the required buttons, the Samsung screen shows with RECOVERY MODE in small letters at the top of the screen, but it then goes blank, vibrates again and boots normally
I was advised by my Dad to use CyanogenMod Installer to get going, then just flash the ROM I want, but even that seems to fail.
And I have indeed gone for the Windows option, far easier using Odin to flash!