Every five years, your church building must be inspected by a suitably experienced and qualified professional, appointed after consultation with the Diocesan Advisory Committee. They will help you make sure your building is kept in good repair. The guidance attached here will help you with choosing and working with your Inspector, and preparing for and receiving the report.
The Miscellaneous Provisions Measure 2019 (Section 7) has received Royal Assent and is likely to come into force soon, which makes some changes to the process for appointing Inspectors, and also who may be thus appointed. A summary of the changes and reasoning can be read here.
The guidance from the Church Buildings Council, and new Diocesan Model Scheme (which can downloaded below), describe the legal situation when the Measure does come into force. The Diocesan Synod will have to have approved the new Scheme. Check with your DAC if in any doubt.