Assuming you can load the PDF OK, and TC can "see it" (so at least can interact with it on the most basic level), and it's not a protected PDF (you'll need a third party bolt-on for those) ....
You can simply click it to give it focus, then send it keyboard shortcuts (CTRL A then CTRL C) which will select all text and dump it into the clipboard. Then just take the clipboard content into a string in your script and do whatever you need to do with it.
This only gets raw text. No images. No formatting. But if it's just the text you need, it's a simple and effective solution. I've used it many time for validating document content, in the same way you'd screen scrape from an application.