Appraisers who don't have a lot of experience having their work reviewed by auditors often find it a terrifying (and depressing) experience. There isn't a lot of guidance on what to expect and what to offer. One simple and helpful summary of best practices has been released by the International Valuation Standards Council: A Guide to the Audit Process for Professional Valuers. It's available for £10 from the IVSC bookstore.
Incidentally, the International Valuation Standards (IVS) are also available at this bookstore for £40. The current version was released after substantial revisions (to make them shorter) in 2013; IVSC intends to release the next update in 2016.