There are various ways to bypass/remove password protection on VBA that is embedded in excel and other MSOffice files.
All of them require you to be running windows though I think.
Here are two threads on stackoverflow:
https://stackoverflow.com/questions...the-password-on-an-excel-vba-project#19704979
https://stackoverflow.com/questions/272503/removing-the-password-from-a-vba-project#7835861
There are a few other methods, but the ones listed in those two threads contain the most common ones that I am aware of.
And the best method to use would depend on the version of excel that was used to create the file and the file-format it has been saved as.
Having said all of that:
Although you have legitimate reasons for bypassing/cracking the password on the VBA in the spreadsheet AND there are lots of documented ways to achieve this - I don't know where you stand from a legal standpoint regarding cracking the password and removing the protection.
I thought the UK government had already committed themselves to releasing public data using open document formats.
Ref:
https://www.gov.uk/government/news/open-document-formats-selected-to-meet-user-needs
So another option might be to contact the HSE, explain what you are doing with Ian's RosterBuilder software and ask if there is any possibility that they can start providing the spreadsheet in the open-document format too, with any necessary macros included in the document.
That way, you won't have to resort to cracking the password protection on the VBA in their excel file and you'll have all of the data in the format you require it to be in. Might be worth a punt!