See here:CanCheckOut method
Example:This example verifies that a workbook is not checked out by another user and can be checked out. If the workbook can be checked out, it copies the workbook to the local computer for editing.
Sub UseCanCheckOut(docCheckOut As String)
If Workbooks.CanCheckOut(Filename:=docCheckOut) = True Then
MsgBox "You are unable to check out this document at this time."
This may help: http://office.microsoft.com/en-001/excel-help/excel-services-i-the-basics-RZ010285479.aspx?section=2
In the SharePoint document library, the Web address, or URL of the library to publish to, is visible at the top of the window. The New button is visible, which means that the person who sees the button has the SharePoint permissions to save files to the library.
In Excel, the cursor clicks the Microsoft Office Button Button image, points to Publish, and clicks Excel Services.
In the File Name box, the document library URL is entered (leaving "Forms/AllItems.aspx" off at the end). In the Save as type box, Excel Workbook is selected (there are only two Excel file formats to use when you publish a workbook to Excel Services: Excel Workbook and Excel Binary Workbook). The cursor clicks Save. The document library appears in the Save as window.
A file name is entered, and the cursor clicks Save again to publish the file to the document library.