Sure, I can help you create a leave planner in Microsoft Excel. Here are the steps:

1. Open a new Excel spreadsheet.
2. In the first row, create column headers for "Employee Name," "Start Date," "End Date," and "Total Days."
3. In the "Employee Name" column, list the names of your 10 staff members.
4. In the "Start Date" and "End Date" columns, create a row for each month of the year (e.g. January, February, March, etc.).
5. In each cell of the "Start Date" and "End Date" columns, create a drop-down calendar using the
   Code:

   Data Validation

   feature. This will allow you to easily select the start and end dates for each employee's leave.
6. In the "Total Days" column, use a formula to calculate the number of days each employee will be on leave. The formula should subtract the start date from the end date and add 1 (since the employee is also off on the end date). The formula should look something like this:
   Code:

   =IF(ISBLANK(B2),"",DAYS360(B2,C2)+1)

7. Use conditional formatting to highlight any cells where an employee's leave overlaps with another employee's leave. This will help you avoid scheduling conflicts.
8. Save the spreadsheet and share it with your team.

Alternatively, you can search for free leave planner templates online. There are many websites that offer free templates that you can download and customize to meet your needs. Some popular websites include Vertex42, Smartsheet, and Template.net.