Under the Representation of the People Act 1983, candidates are entitled to use certain rooms free of hire charge for election meetings. Section 95 makes provision of this right for the purpose of holding public meetings in respect of Parliamentary elections and Section 96 makes equivalent provision for local elections.
It should be noted however that this is subject to availability and if additional costs are incurred, for example, to pay a key holder to be on site or for additional heating, lighting, or any other reason, such costs are due to be paid by the relevant party or candidate.
This element is a matter between the party/candidate and the venue and should be settled directly with them. It is not a matter for The Returning Officer.