Short answer: you will have Business Class lounge access at all airports on the itinerary (not necessarily titled 'Galleries' in all cases though).
Longer answer: this will either be by dint of travelling outbound and inbound longhaul in Club or, if you are travelling on revenue (rather than redemption) tickets, then your domestic sectors will almost certainly have booked into 'J' which is Business UK and affords lounge access anyway.