I have been sent a message containing an attachment but I am unable to read it because it is in Office. Is there any way I can access it without having to purchase Office
I expect Buenchico will be along sometime with a more comprehensive answer [excuse my presumption Chris] but, as far as I know, most decent word processing software allow you to open "alien" files as unformatted text or similar, from which you can usually pick out the essence of it.
As has been said, a file can't be 'in Office'. Check the file extension to see what type of file it is. (.doc, .docx, .xls, .accdb, etc). Then look in the list here to see which Microsoft Office program is needed to open it:
https://en.wikipedia.org/wiki/List_of_Microsoft_Office_filename_extensions
The vast majority of those files can be opened by free software, such as OpenOffice
https://www.openoffice.org/
but just ask us if you need help with a specific file type.