FNRttC York to Hull - Trains (back) to York on Sat 24 June 2017?

[SA_SA_SA_SA]

If I arrived at York  early enough I might consider the FNRttC but what about the return to York?:

should a northern trains all day off peak ticket from Hull to York be bought well in advance (£20) or would buying a ticket on the day be affordable (and would trains be likely to have (non-bookable) space for bike anyway?)

[telstarbox]

That ticket costs the same if you buy on the day - no need to book in advance.

[SA_SA_SA_SA]

Thanks.