They will want what to see your qualifications, 2M insurance, complaints forms (download from niceic), health and safety documents, tester calabration, part p building regulation and electricity at work regulations 1989( download from net), certificates of 2 jobs done and access to these jobs. See you do all testing over the two jobs (1 of each test) R1+R2 on the cooker, maybe a ring test etc. They may ask you questions like permitted insulation resistance and test voltage, max Zs for a circuit, permitted rcd trip times.
My advise is to put it all in a folder in sections to make it easy for them to see. All the books as well, bs7671, gn3. If you don't have something then they may just note you need to get it.
Good luck.