If a Returning Officer wishes to use a room within a publicly-funded school or any other publicly-funded building he is entitled to do so free of charge. (Those who control the relevant building have no say in the matter). However he is obliged to defray any expenses thus incurred by those in control of the building.
[Section 22 of Schedule 1 to the Representation of the People Act 1983]
So if a council-funded village hall is required as a polling station, on a date with a prior booking, that booking must be cancelled but the village hall can require the Returning Officer to repay any monies that they've lost through such cancellation.
With any other proposed polling station the Returning Officer can't insist that prior bookings be cancelled. However it's common practice for village halls (etc) to have a term in their booking conditions which states that bookings may be cancelled if the premises are required for use as a polling station.