Getting tens, or even hundreds of GB/month over ordinary cellphone plans will probably be expensive no matter what country you buy the SIM in. You should monitor the usage and figure out what's stealing most bandwidth.

Video meetings probably eat a lot. Is it really needed to use two-way video in the meetings? We often turn off video and mute the sound when we don't have anything to say, even when participants are sitting on unlimited bandwidth. If you absolutely must have the video on, try at least to sit as still as possible.

Other things that shouldn't eat a lot of bandwidth may sometimes do ... like, fetching mail should be really light-weight, particularly when using IMAP, but somehow my previous phone was eating up the quotas simply by continuously checking for new mail.

Also, go to land and find hotspots for getting the most bandwidth-intensive tasks done.

According to the new "roam-as-home"-rules, it should be possible to use the home provider, the exception is if you have moved abroad and is obviously abusing the "roam-as-home"-rules. Two months ... well, perhaps that's within the framework, but sounds a bit harsh if you ask me. Get two SIM-cards and send one of them to a friend in the UK every month to "refresh" the quotas.

I'm sure there exists some smart solutions for IP-over-phone or IP-over-SMS that one can (ab)use ... :-)