Thank you! And I would like to reassure anyone who was concerned and shocked about my lack of general knowledge that I do know what time zones are, and that there are different ones. I just didn't know that NI is in the same time zone as England/Scotland/Wales.
If someone asked me, I would have said "I imagine so", but I've never had a reason to learn/find out. I've never been to NI and I don't know anyone who lives there. So I'd have guessed that it was the same, but I wouldn't have wanted to state it as a fact.
Why? Well, the island of Ireland is further west so it wouldn't be unreasonable for it to be -1. In fact, on the map, the majority of the island is actually in the -1 zone even though it is in GMT/BST time zone. So, it might've been that Ireland is 1 hour behind and NI is the same so as to be in step with the rest of the island. Many countries cross multiple time zones, even not huge ones.
Maybe in UK schools you get taught that all 4 nation states of the UK are in the same time zone. I wouldn't know, because I didn't go to school in the UK. I am French, I went to a French school in France, and I learned things like what the main exports are from the midi and which countries were mean to the French and when.
I don't think any of that makes me lacking in basic intelligence, but I'm prepared to accept I'm lacking basic general knowledge if that's the consensus (and it seems to be!).