I got given mine just before I left Spain. In order to do the things I needed to do a smart phone was the only realistic proposition. Now I carry it when I go out for similar reasons to you. I hadn't had any sort of phone for the ten years in Catalonia. I can't say I missed them.
However, I think the majority of smart phones can do something that can save money and help limit aimless internet wandering. It's called USB tethering. Once set up and connected by a USB cable the phone can act as a modem for a full sized computer with keyboard and screen.
I had a broadband wired internet connection installed when I moved in. The deal was okay, twenty pounds a month for adeqaute speed on a contract that lasted eighteen months. I didn't notice the first bill payment but on the second I saw it had gone up to fifty two pounds a month!
It gets worse.


During my recent sickness relatives suggested I subscribed to Netfix and Prime and I could watch movies on the computer to help keep me entertained. About ten pounds each.
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Then there's the phone; that's another ten pounds for 7GB of data a month with free text and calls (there are of course limitations).
That lot adds up to eighty pounds a month to talk to people, which I'm not overly keen on, and watch shite films.

I've watched some serious crap over the last few weeks and I've done it because it was there and an easy option.
My data usage before Netfix and Prime arrived on the computer was around 6GB. I haven't got any friendlier so I guess my usage is pretty steady.

My phone will cover 6GB and more. I can get a further 5GB of data for five pounds.
That knocks sixty five pounds a month off my bills and will probably improve my mental and physical health in the process.
Netfix and Prime have gone. Wired internet connection is going at the end of the month. I've tested tethering out on all three of my computers and it works well.
Course, if you don't hear from me for a bit don't assume I've dropped dead; it's possible I've overlooked something on the technical front.