Maybe just upgrade in aircraft for strike days if anything? for example F70 to B737, just so theres additional capacity if needed? Lets not forget that EZY also fly these routes so pax may have option to re book through BRS or LTN to AMS, CDG, NCE, CIA etc
I believe (correct me if wrong) that LGW is no longer BAA run, so plenty of options for LHR pax without maybe the need of extra flights through Brizzle.