Let us know how you get on!
For the record, this is what ExpertFlyer shows (solid blue seats are already allocated). Not especially helpful <72hrs out.
FWIW it doesn't look an especially full flight in Y (UK PoS: F6 A4 J9 C0 DC RC IC W9 E1 TC Y9 B9 H9 K9 M9 L9 V9 S9 N9 Q9 O9 G9). So you could sort the five out leaving an empty middle seat somewhere within the five. Hope that seat stays empty, and then ask the crew nicely whether you can move into that seat on board.
One for the experts: does Theoretical Seating take fare paid into consideration?