Stuarrt, Since you say you are new to film and perhaps only experienced with digital, here are some very general practices to help you get started. When it comes to color negatives (aka C41), they are considerably less prone to burning out highlights. Digital users have known since the first models to use the histogram to prevent overexposing as well as shooting in RAW. By comparison, color negatives and b&w (chromogenic and true b&w) film have a much wider tolerance for overexposure by comparison as shown below.
As you can see, by 3 stops overexposure, digital files are no longer recoverable while even Kodak Ektar 100 is still very workable and Kodak Portra 400 has much to go.
Here is the full range that I shot of Kodak Portra 400.
Simply, this means err on the side of overexposure as you have plenty of latitude to recover.
In practical application, you can shoot an extremely wide latitude scene and recover detail in both shadows and overexposure as in the example below as well as your own example that I adjusted.