Riiiiiight. Think I /might/ be getting somewhere. I just managed to get it to work from my Pi using curl and the --digest option. What's the difference between basic and digest authentication? I'll see if I can get that working in Tasker now.
That's true. I'm thinking it might be easier to change the times or switch it off when I want to if I do it on my phone. All working now though which is nice.