on Virgin trains to the North West, if you travel off peak out and most of the journey is off peak back can you get off the train early at the last off peak station.
It depends on the precise wording of the ticket restriction. For a £58 Off-Peak Return Milton Keynes C - Liverpool L St, the restriction is
9I and the part if that relevant to Milton Keynes is:
These restrictions apply MONDAY to FRIDAY. By any train on other days.
OUTWARD TRAVEL: You may travel on any train that is scheduled to depart MILTON KEYNES CENTRAL before 0430 and at or after 0951.
RETURN TRAVEL: You may travel on any train that is scheduled to arrive MILTON KEYNES CENTRAL before 0639 or at or after 1048.
http://www.nationalrail.co.uk/pdfs/SVR_9I.pdf
The 1640 from Milton Keynes is permitted with an Off-Peak Return, but the 0527 from Liverpool is not because it is due to arrive Milton Keynes at 0712. The wording of the restriction means that you cannot travel Mon - Fri on the 0527 from Liverpool for any part of that train's journey.
You are right to point out that the £44.70 Off-Peak Return Rugby - Liverpool L St, has minimal restriction
2T:
OUTWARD TRAVEL: By any train except those timed to depart Mondays-Fridays before 0415.
RETURN TRAVEL: By any train except those timed to depart Mondays-Fridays before 0415.
http://www.nationalrail.co.uk/pdfs/SVR_2T.pdf
But this ticket cannot be combined with a Rugby - Milton Keynes Single or Return ticket on a service which does not call at Rugby and, although the 0527 calls at Rugby the 1640 does not.
If it really is essential that you use these two trains, and you don't want to pay the Milton Keynes C - Liverpool L St Anytime Return price of £197, two suggestions are:
- if you're planning any other significant travel on that route within 7 days, buy a £199.30 Milton Keynes C - Liverpool L St 7-day Season Ticket. This is valid for unlimited travel over a wide range of routes in the Midlands, Merseyside and Greater Manchester.
- if not, buy a £61.40 Milton Keynes C - Rugby 7-day Season Ticket and a £44.70 Off-Peak Return Rugby - Liverpool L St, a total of £106.10. Unlike a combination of Single or Return tickets, one Season Ticket may be combined with one or more other tickets on a train which does not call at a station where you change from one ticket to another. See NRCoC Condition 19.
EDIT You may be interested to know that the £58 Wolverton - Liverpool Off-Peak Return, which also has restriction
9I, is in effect valid by any train which avoids doubling back through Milton Keynes C. Search for "Wolverton - Liverpool avoiding Milton Keynes". It allows, for example,
Friday: 1733 Wolverton - 1817 Rugby 1823 - Liverpool L St 1952.
Monday: 0527 Liverpool L St - 0652 Rugby 0712 - Wolverton 0751.
2nd EDIT Even better,
East Coast will sell you a £58 Wolverton - Liverpool Off-Peak Return with reservations for the Friday 1640 Milton Keynes C - Liverpool L St and Monday 0527 Liverpool L St - Rugby. If you use this ticket Milton Keynes C - Liverpool L St - Rugby and also buy the £12.60 Rugby-Milton Keynes Single suggested by crosscity in post #4, you'll be able to travel on the trains you proposed for £70.60. You don't need to start from Wolverton, but I would print and carry a copy of the journey itinerary in case you're challenged.