Thanks for the replies. I looked up each one individually. One of them, basil, can handle up to 35c in full sun so I've put that with the bell peppers. These two plants are the only ones I've found so far that can take the heat and full sun all day. Everything else withers within half an hour, so we've had to be really careful. Parsley (I think) comes second for temperature tolerance, up to 30C. The other two can only tolerate 20-25C so they definitely need to be indoors. The difficult part is providing
enough sun indoors. Some of our windows get maybe 2 hours sunlight in the morning but that's it.