Radio Failure procedures are always an interesting topic for discussion when all else fails because, despite all the written rules, the possible scenarios are almost infinite.
My personal interpretation of your specific questions are -
1. continue at FL340 and climb to FL360 when you reach the point at which you flight-planned to climb
2. I would interpret your early climb to an unplanned FL380 as amending your flight plan, so I would expect you to continue at that level
However, in all real cases of radio failure most controllers will anticipate any of the above options (and a wide selection of others), basically keeping everybody else well out of your way!!!
Remember to transpond the appropriate code so that we know that you know you're out of contact - not just day-dreaming up there!!!
Finally, in this day and age, especially over France, keep a sharp look out for a Mirage in close proximity shortly after you lose contact with ATC.