Hello,

I plan to travel from October for up to a year, going to South America/India/South East Asia and possibly southern Africa too. Does anyone have advice on finding a good worldwide sim?? I have never got one before so am not sure what the cost should be or what to look out for when choosing one?? Any reccomendations gratefully received!

When I travel I get data only eSims from Airalo dot com

I have done many around the world trips and in the past, have always just picked up a local sim on arrival in each country. I have desk drawer full of now redundant sims. Now like J62 above, I just load up an esim from airalo and activate when needed. There are lots of plans available , country or regional specific or global with differing contract lengths , prices etc. Most phones < a few years old have esim capability. Just down load the appropriate app for your particular phone.
Most sims only include data and not calls but I have never found that an issue and just use WhatsApp , messenger or FaceTime

Check out Tello.com. It's my carrier for my flip phone--I do not use a smart phone-- which could never be used with a connection to free WiFi while in Europe, but this year allows for roaming at low cost which allowed me to call without depending on free WiFi. I think that their US chip in a smart phone would allow WiFi and roaming connections around the globe.