Hi @simonsmith, thanks for reaching out. For the Tobii 4C Eye Tracker, we recommend using the Interaction Library API.
We have created a full walkthrough tutorial and sample code you can use @ https://developer.tobii.com/product-integration/interaction-library/getting-started/
This software does not require the purchase of any special licence, so should be ready for you to get up and running directly!
Please try it out and let us know how you get on. Best Wishes.