1gb month is quite generous but that’s assuming you have good wifi and I recall from your original post that was an issue. I do app updates/downloads, photo uploads etc and buy music / movies via wifi so it keeps mobile usage down! Note you can do this via your computer and then sync the phone which minimises data. If you have bt internet they have lots of wifi hotspots as basically every bt router is a hotspot. Generally you can upgrade your contract at any time so you might try a limit to start with depending upon costs, personally next time I’d go unlimited as extra cost is limited these days with 3 who I will use.
Edit: I have my iPhone / iCloud setup so that all synching is done wifi only (so no mobile data) so when I take photos they are transferred to cloud and other devices only once I’m back on wifi, ie at home (or in pub, most of my wifi hotspots are pubs/bars with free wifi).