If it is one of those funny tickets, you run the risk of coming across staff at a gateline who will tell you that you can only break your journey if you're travelling on the shortest route between the stations shown on the ticket.
Taking a printout from the NRCoC is advisable - but if you can't get them to allow you to leave the station with your valid ticket, you might need to call the BTP.
Also, I'd excise cation with using tickets not shown as valid on NRE. I personally would not want to defend using a such a ticket in court - presumably you'd use the NRG in your defence, which does say that you need to use the NRE Journey Planner to validate any routes you've found.