I have a couple of Toggle SIMs too. Toggle offers a terrific system but their customer service is beyond awful. Still, if you go in with your eyes open, it can be a good deal.

Toggle's instructions say the card will automatically respond when you enter a different country. I burned through £16 of credit in one call when this did not work for me on returning to the US. After much frustration I discovered that requesting a "deadlock letter" was the incantation that shook loose a refund.

I was concerned about the very high cost of data outside the UK (£0.15/MB in France), but I found that disabling sync and using data cautiously kept the cost quite reasonable.