I guess that depends what "accessible via G-only" means. As I understand it, if you're in E for example, you go from E to the temporary E1 to F rotunda corridor and then temporary F rotunda to G corridor (which takes you to a point on the old F-G corridor) and then from there to the lounge. AFAIK, the old route that ran in front of F1 to F4 will be closed - that's why the temporary the F rotunda to G corridor. There will still be an inside security route from F to G.