This letter is dated 2nd July. When did you receive it?
You have only until this coming Thursday to get your response back to the police. Later than that and you commit an offence which carries six points.
At the risk of appearing pedantic and/or for the benefit of the hive mind, the 28 days to provide the required information
begin with the date of service - in other words, it's 27 days
from the date of service.
If the case isn't nearing timeout, the police do not usually prosecute for the s. 172 offence if an otherwise acceptable response is received a day or two late - but if there is time to comply with the legal requirement, there is little point risking it, or leaving it to an incorrectly calculated "last minute".