I am going to send my first application for British Passport and I have just realised that my countersignatory did not write the date in the back of the photo. I have impulsively written the date. Will I have problems because of this?

I am an EU citizen applying for UK citizenship on the basis of 5 years residence in the UK. The online form requires to send proof of living in the UK for the past 5 years and this should include letter from employers, or govern departments. Would Tax Returns for self-employed individuals or letters ...