I would be interested to know this too.
Are the airline going to penalise you if you don't make the LHR to DUB return journey basically leaving the airport with your hand luggage (no you couldn't have any hold baggage as this would be being transferred to the DUB flight)
You can do the same with indirect flights from Manchester to last Vegas via Heathrow with back, it's cheaper than from Heathrow direct even though you're on the same flight from Heathrow. Silly really but there's more competition from Manchester so prices are lower
We did this exact flight . Got them even cheaper at around £305 pp . We wasn’t going to tKe the risk with Ryanair having a delayed flight , as if this happens you would lose all flights then , so we still booked Ryanair flights but for the day before and after our return, then booked the premier inn Dublin at the airport. 2 nights €100 , flights £9.99 each way . But with luggage just over £100 . So worked out £405 pp even with 2 nights hotel . We saved £400 total , which was extra spending money . Would I do it again ? NO We fly next May with Thomas Cook £505 pp but that’s premium both ways direct from Manchester
i never take the last flight back to dublin arrive at heathrow and take train home