A cover letter is not mandatory, but in my opinion a highly desirable addition to the questionnaire. This is your only opportunity to clarify some points in the questionnaire, tell your story and prove the authenticity of your relationship .
How to write and what to include in the cover letter for a visa?
There is no sample, the letter is written in free form. If you have not downloaded an example of my letter, you can do it here.
Example of letter structure:
Your home address
Appeal (Dear Sir / Madam,)
1st paragraph - where, when and under what circumstances we met.
2nd paragraph - how our relationship developed, how many years we have been together and when we got married.
The third paragraph is the history of my English visas and the introduction to the further tablet with all our trips together.
Further, the plate with the trips with the indication of dates and places.
4th paragraph - a description of my education and plans for finding a job in England.
5th paragraph - information about where we will live.
6th paragraph - a list of attached evidence of our relationship .