Your best bet is to look on the East Coast website, find the calling points of the train and try splitting to those ones rougly half-way (Off-Peak [month] Return tickets are usually only offered on longer journeys, for some value of long).
Advance tickets at £13/17 each way are available on this route. However the quota for that weekend has not yet been released (they are available for the previous weekend). When released they will probably be the cheapest way there & back.
Advance fares start at £13 single (So £26 return), but you have to stick to the booked trains. They haven't been released yet for your dates, but they have for the week before, so they should be released within a week.
Hi calc7, OwlMan and aleksander thank you for your very timely responses. You've been a great help! Ta. Hugh --- old post above --- --- new post below ---
Hi I like the price! But advance tickets with which rail companies, please? Thanks again! Hugh