could not create reboot volume for apfs install

hello all .. decided to factory reset my old trusty 2009 Mac 276 , running high Sierra

seems its not so easy .. after googling to find way round the 'could not create reboot volume for apfs install ' problem I found pressing option cmd r buttons on restart .. I should get the globe icon . however all I get is intermittent icons apple logo and no entry circle sign .. any boffins out there ?

many thanks Olly