A cover letter cannot save a weak application, but it can lose a strong one. These six turn up again and again in files we inherit.
First, hedging about your return. "I intend to come back if everything goes well" invites the caseworker to imagine the version where it does not. State the tie you are returning to and evidence it.
Second, contradicting your own documents. If the letter says fourteen days and the booking says seventeen, the caseworker has stopped reading your letter and started auditing it.
Third, explaining a refusal you have not declared. Declare it first, then explain. The other order looks like it was extracted from you.
Fourth, arguing law. You are not filing a submission. State facts and point at the evidence; the officer knows the rules better than either of us.
Fifth, borrowed phrasing. Template sentences are recognisable, and a letter that reads like ten thousand others carries no weight at all.
Sixth, length. Two pages is generous. If the file needs more explaining than that, the problem is the file.
