I'm planning a much-anticipated return to London at the end of August and visiting Bletchley is a must-do, so I'm looking at train websites and need a couple of things cleared up:
Is there a preferred website for buying tickets? I see there's more than one railway, but looks like I'd leave from Euston station. I've been poking around trainline.com but can't tell what time is considered officially off-peak; I plan to travel on Friday, August 31st--leave around 9:30 am, return leave at 5:30 or so since closing time is 5:00. Seems like I can get an open return ticket for any train that's off-peak, but can't tell when that is.
I'm okay with selecting a definite return time, based on other comments I've read in the forums I think I can easily spend 6 hours between Bletchley and the Museum of Computing, having lunch, etc.