print("Hi!. Script Started")
# code to load webpage, automatically fill whatever can be entered
x = input("Waiting for manual date to be entered. Enter YES when done.")
# Enter the data on page manually. Then come back to terminal and type YES and then press enter.
if x == 'YES':
    continue_script_here()
else:
    kill_script_or_something_else()

WebDriverWait wait = new WebDriverWait(driver, 100);
//whatever time you think is sufficient for manually entering the data.
WebElement element = wait.until(ExpectedConditions.elementToBeClickable(By.id(>someid>)));
if(ExpectedConditions.attributeToBeNotEmpty(element,"value"))
{
  //continue with the automation flow
}

driver.findElement(By.cssSelector("body")).sendKeys(Keys.CONTROL +"t");
driver.switchTo().defaultContent();

for(int i =1;i>0;i++)
{
 ArrayList<String> tabs = new ArrayList<String>(driver.getWindowHandles());
 if(tabs.size()==2)
 {
  //keep checking for the point when the number of tabs becomes 1 again.
  continue;
 }
 else
 {
  break;
 }
}
//your rest of the automation code