Don't panic Mr Mainwaring!
So long as you have a job to show them, you have completed the installation certificate and you have the reference books and insurance certificates needed, then you will be OK (so long as you have paid!).
They are not there to trip you up just to check you know, or can look up, the knowledge needed, particularly for the compliance with building regulations.
If there are things that you have not got ready yet then there is still the option to be able to prove these things later (such as emailing a copy of your MFT calibration certificate) and you will still be accepted.
Keep calm, it is not as bad as it sounds, and good luck.
(also have a read of the similar threads further down the page ↓ , they will probably say the same thing)