Not let onto my Eurostar train

I talked about this before in a live video, but if you ever book a trip on Eurostar, arrive early!!! I thought it would be like greyhound or megabus or anything else that says arrive 30-45 minutes early, but you know it doesn’t actually matter as long as you’re on time. But no, it matters. And while it was still my intention to get there a half hour early, my sister and I had some delays that didn’t allow for that. So we arrived with 10 minutes to spare, and were told that we couldn’t get on because we had missed our boarding time. What?! I knew the train hadn’t left, so I was confused. But then I noticed the TSA-like security line. So yeah, it’s like the airport. My sister and I had to pay an EXTRA 30 POUNDS EACH (~$44) to get onto the next available train from London to Paris! So I learned that lesson the hard way so you don’t have to. Get there early!