I think this is getting a little complicated. Firstly, the council is a corporate body, a single entity if you like, regardless of those who make up the council at any time. Decisions made now for the immediate future are binding whether or not there is an election or simply a different set of people in that "committee". Once a decision is made most standing orders say that it cannot be revisited unless there is a material change in circumstances (and a change of opinion is not a change in circumstances). That does not, of course, mean that a decision now is binding forever, but like all decisions may need to be reviewed (if not necessarily changed) over time.
As I understand the exchange here the council want to agree an event/activity that will take place during the next financial year which, presumably, has been included in the budget for next year anyway. I can see nothing to suggest from what has been said that the proposal can't be put now, regardless of the fact that the actual event takes place in the next financial year. These things tend to take a while to organise anyway.