At the moment those rules do also apply to the UK.Also, anyone traveling with Europe being part of the itinerary should get informed about your air passenger rights. The EU rules apply to any flight operated by a carrier with its seat within the European Union as well as to any flight departing the EU regardless of carrier.
https://europa.eu/youreurope/citizens/travel/passenger-rights/air/index_en.htm
The UK is not part of the EU and those rules don’t apply to UK carriers or flights departing from there by non-EU carriers. However, the rules also apply to Switzerland, Norway and Iceland as if they were EU countries.
However depending who is striking you may not be able to claim. In October 2020 my flight was delayed because air traffic control was striking and that was outside the airline’s control, so no compensation was paid.