Any question answered...

From: http://www.nationalrail.co.uk/times_fares/ticket_types/46590.aspx

Break of journey

Break of journey is allowed on the outward portion of Off-Peak tickets unless otherwise indicated by a restriction shown against the ticket's validity code and in all cases on the return portion of Off-Peak return tickets.

You may start, break and resume, or end your journey at any intermediate station along the route of travel on Off-Peak tickets unless the ticket restriction for the journey you are making does not allow it. If you intend to start, break and resume, or end your journey at any intermediate station, please call 03457 48 49 50 to check if it is available on your specific journey.

Worth calling just to check but it sounds ok (I assume the "and in all cases on the return portion" means it's ok in all cases, the language isn't perfectly clear).

I wouldn't risk the ticket in the barrier, go to the wide luggage barriers where a guard/ticket-inspector is lurking and ask to be let through. Usually they let people through without looking at the ticket you're waving at them.