Yeah you'll be fine, the staff at Oxford Road are a relaxed lot. I'd still board at Piccadilly myself but that's only for the higher chance of getting a seat, as the Preston trains can get quite busy.Yes, the ulverston to manchester leg wouldn't work in the barriers at Oxford road but the staff let me out.
Too cold and wet to walk to Piccadilly so feel like i should be fine
Just to second what people have said here, they are more relaxed at Oxford Road.
I would not want to take my chances my ticket only being valid as far as Oxford Road and then getting off the train at Piccadilly as I could imagine Northern's contractors taking an issue with it. But you are starting your journey so its slightly different.
I once had a Manchester to Newcastle Advance and I specifically inputted Oxford Road as the starting point. I received two mandatory reservations: Oxford Road to Piccadilly and Piccadilly to Newcastle.
Yes, the ulverston to manchester leg wouldn't work in the barriers at Oxford road but the staff let me out.