Ho-Ho-Ho Merry Christmas!
I'd echo the above. The general rule I'd apply is there's no rule. Expect anything and all that. Yes the book would say that you should follow the SID, then after 3 or 7 minutes depending on whether you were on a heading or your own nav climb to your Flight Planned Level etc. But basically as soon as the controller believes you have suffered an RT failure they'd be trying desperately to get traffic out of your way. And yes a possible U-turn and return to origin would be half expected too.
I would emphasize though that it's 'as soon as the controller' gets the message, so I would ALWAYS prefer you to 7600 asap and then common sense and an awareness of the procedures should allow for a safe flight either to your destination or return to origin.
In line with the above I'd hope for a moderate ROC or descent so that we can make an educated guess of your intentions and give us a fighting chance of maintaining separation from everyone else. Having said that, keep a good look-out, be aware of your TCAS, try all means of comms, 121.5, mobile etc. And if you're 7600'ing for a while don't be surprised if you are joined by a friendly fighter!
That's my sixpence worth anyway, gotta grab myself a whiskey! Happy Christmas to you all and bad luck if you're working (or stranded) tomorrow, it was me last year.
Have a good one!