Well done IanT, it is something that needs to be done and once it's done noone can take it away from you. It has such a good ring to it and it's not something just anyone can do.
The last ton I did last year was also a spur of the moment thing. I had intended on doing one of my regular routes of about 60mile, but when I got to my turn point I phoned my wife and told her I was going to be late and kept on going. Trouble was I had no food with me, so I stopped at a small rural shop and bought some fruit and cereal bars and extra water as I only had one bottle as well.
I think you would be able to do it no bother. Just keep heading away from home 50mile. You will have no option but to cycle home
. It's more of a mental barrier.