To avoid any delay, send him and to your lender the following documents:
1. Proof of your ID
This means a copy of your passport, but remember that has to be certified. You can get your passport certified at any post office: bring there both the original document and its copy, and then fill the ID Checking Service Form.
2. Evidence of your earnings
This means your paychecks and P60. The P60 is an official document released by your company (before May 31) that shows the tax you’ve paid in the last tax year.
In case you are self employed you'll be asked to show copies of invoices, your business bank account statements and your tax return. They accept official digital files.
3. Proof of your address
Any official letter addressed to you and issued within the last 3 months. It can be for example an HMR&C notification letter, a local authority tax bill (council tax), a letter from bank, utility bills (except mobile phone bill), TV licence etc. This document has to be provided as certified copy too.
4. Bank statements
Bank statements of the last 3 months. They accept either certified copies or official digital files (pdf printed from the bank website).