You may be able to charge for lettings (and make a profit)
Your governing board can decide how the school premises are used, including whether they can be hired out. This is because the board is responsible for the day-to-day running of your school land and buildings, and for the health and safety of pupils.
Your school is also allowed to make a profit. Any profit you make must be reinvested in the school.
You must work closely with your local authority (LA), as your LA has some powers of direction over how your school premises are used.
This is set out in the Governance Handbook (see sections 6.12.1 and 6.12.3).
Voluntary-aided, voluntary-controlled and foundation schools
In addition to above, you must also work closely with the trust that owns your land to decide how your premises can be used.
This is explained in section 6.12.1 of the Governance Handbook, linked above.