Disclaimer first. I am not a coach. Have swum Masters for 18 years and raced in all of them. From my experience and so called knowledge I pass this on. Hope others respond.
Exercise physiologists say that one does not lose any conditioning until after five days of non activity. Also the axiom of "if you are not is peak form now - five more days of work won't get you there" applies to us all. In fact I feel that one is better served to be so well rested or tapered come race day that one feels as strong as a horse.
This is especially true in the case of older athletes. I don't recall if you would be considered an older athlete. :0)
If you can't stand to be totally idle at least cut out the hard sessions.
Whatever you do this week I wish you the best of luck on achieving your goal.
May we swim with ease at the speeds we choose.