We arrive in London next week (Thursday), and concerned with the current strikes affecting Trains & Buses. We must get to Amsterdam next Sunday afternoon to meet up with a Tour group, and have tickets on the Train. ***What are the other options & recommendations to get there if the slowdowns or strikes continue as it looks...?
I don’t think there are any strikes next week.
be sure to check in plenty early for the Eurostar. One hour is current recommendation but I'd be earlier. The French Border Control before getting the train can take some time especially this summer.
and you are doing it on a Bank Holiday weekend.
Actually it looks like Eurostar suggests 90 minutes. Unless you fall into one of the other categories.
https://www.eurostar.com/us-en/travel-info/your-trip/check-in
By law,, rail worker unions must give two weeks notice of any strike. That means they won't affect you because there are no strike notices on those days.
But if there is a problem, there are numerous flights between London and Amsterdam.