Acknowledgement of service time limit

I came across this requirement:
Within 8 days (including the day of receipt) of the Petition and statement of arrangements from the court, the respondent must send to the court Form D10 (acknowledgement of service).

I want to file the petition but we are both going abroad (to our respective families) in 2 weeks time, so I am not sure if it is best to wait until we are back.
1. How long does it take the court to send the forms to the respondent?
2. What are the implications if he doesn't reply within 8 days (simply because he is not in the country at the time the documents come through the post)

I am a bit concerned about leaving it too long as it is coming up to 6 months after the more serious examples of unreasonable behaviour I have listed and dated in the Petition.

1. How long does it take the court to send the forms to the respondent?

Depends on the court for most a few days to a week.

2. What are the implications if he doesn't reply within 8 days (simply because he is not in the country at the time the documents come through the post)

Very little and its quite common, if he wont respond once back home its then for you to have the Petition served, doesnt sound like this will be needed here though.

He could just send them back to court with a covering letter explaining he was abroad, that will be fine.