Should I be worrying that my United Airlines flight into LHR on March 31 will be somehow affected by the strikes at British Air? United usually flies into terminal 1, Heathrow.
I don't think your flight itself will be affected.
However, any time there is a "disruption" be sure to allow plenty of time at the airport. Assume there will be people trying to get on your flight to get LHR because the BA flight was cancelled and arrive early to check in and make sure you are at the gate by the time required by your airline.
Someone will have read SOMEPLACE that you can just go to the UA counter and get your "BA ticket written over" and will be clogging up the whole system whining when they discover that's only true if you have full fare ticket or BA will have written them over and done something wrong, etc.... :)
I'll allow 3 hours at SFO and check-in in advance. That "carry-on only" thing works for me. If things are messy on the London end of the flight, well, I'm in no big hurry. I've no connecting flight. I plan to take the Tube to the St Pancras area for an overnight stay at a hotel. Then, it's on to Paris by train the next day.
On a positive note: it could clear up the never-ending clutter at Heathrow, and increase "on-time" rates. Here's hoping! :0)