I think I'd be tempted to leave it a few weeks just to see if there are other changes first. You're only away for a short period, so there is a risk of things not fitting together (and ditto with irrops, though the weather in November is always wonderful, is it not?). At some point I'd see whether there was some new DUB or other similar deal going on, and just plug for a full refund. In practical terms you need a 3 hour connection out of T8 after the LHR service and 2 hours from T8 to T7 on the return to LCY.

(Did you check whether replacing CLT with PHL or DCA would work, by the way?)