Mail merge of documents, using a script

I have 21 documents that make up our Health and Safety documentation. Each year, we need to publish an updated version. At a minimum, the date and version number changes. Attached are two sample documents along with a spreadsheet which words or phrases to replace with a mail merge field. I would do this by hand, which would both take a long time and be error prone. I would prefer for someone to find a programming/ scripting solution. The deliverable is 22 documents (I will supply the full set of current documents), set up to mail merge from an excel sheet, and an appropriate script (VB or Phyton) that goes through all the documents, applies the mail merge fields, saves the word doc, and generates pdfs. The mail merge and script should should use relative paths only, as they are kept in the same folder, and be duplicated when a new version is produced. This is because editorial changes are also made in this process. The word documents are in a mixture of word version, you should bring them all up to the same docx version. We employ software developers, who are just too busy with other things to help, so your work needs to withstand their scrutiny. No messy jobs, only professionals, please. Thank you!