a week tomorrow, on Monday, etc.

a week tomorrow/on (some day)/etc.

One week from the day specified. Primarily heard in UK. I'm flying to Ireland a week on Saturday for my brother's wedding. We need that report finished a week tomorrow.
See also: on, tomorrow, week
Farlex Dictionary of Idioms.

a ˌweek toˈmorrow, on ˈMonday, etc.

(British English) (also a ˌweek from toˈmorrow, ˈMonday, etc. American English, British English ) seven days after the day that you mention: It’s my birthday a week on Tuesday.
See also: on, week
Farlex Partner Idioms Dictionary
See also:
  • Friday
  • Monday
  • Saturday
  • Thursday
  • Wednesday
  • a week tomorrow/on (some day)/etc.
  • a week yesterday
  • yesterday
  • by the week
  • week in, week out