UK airfare taxes, duty etc

Thanks everyone for your input. For all those living on the UK mainland, it seems if you want to fly Malaysian airtlines, you can fly from Heathrow for around £300 less if you fly from Dublin via Heathrow as you connect with the the same Mas flight if you were to fly initially from Heathrow. Even if you had to pay a flight of £100 to Dublin and fly back to Heathrow and then connect with the Mas flight, you are still saving.

Is it possible to make the booking for Dublin/Heathrow/Malaysia and forefit the Dublin flight. IE make the Heathrow flight the first flight?

No...if you miss one leg,the whole ticket is invalidated.

complicated....rem prices are going up make a decision quickly ......
either dublin or belfast via heathrow onwards .....i know theres so many options but so little time ....hope it works out

you can fly from Heathrow for around £300 less if you fly from Dublin via Heathrow as you connect with the the same Mas flight if you were to fly initially from Heathrow

Supply/demand, price matching, taxes, etc. This is confusing but very common.

Is it possible to make the booking for Dublin/Heathrow/Malaysia and forefit the Dublin flight. IE make the Heathrow flight the first flight?

As Lucapal points out, your entire ticket will likely be forfeited. You can try to buy the ticket, then contact the airline and tell them that circumstances has led to you needing to take the flight from LHR instead of DUB, but chances are they won't allow you to change it.

What you can do however, is forfeit the very LAST leg of your flight. This sometimes saves you money. I.e., you fly DUB-LHR-DXB-LHR-DUB, here you can forfeit the last LHR-DUB segment, generally without any penalty. This is called "hidden city ticketing". It carries some risks (like rerouting) and is more difficult if you travel with luggage.

The same applies to flying from Detroit to Toronto to London vs. flying from Toronto to London. It's cheaper from Detroit and uses the exact same flights on the exact same airline from Toronto. The difference in price is because of the much higher airport taxes/fees in Canada. The flight originating in the US does not pay those same taxes/fees. When I checked the difference was around $200 per person.

The UK is known to have the highest taxes/fees in Europe.

Leaving out the first leg will as noted result in the rest being cancelled. It's called a 'missed segment' You can however miss the last segment (London - Dublin) as there will be nothing left to lose.

The best place to ask questions of this type is on the Flyertalk forum. There are a lot of well informed (as in more expert than airline staff and travel agency staff) regulars there.
http://www.flyertalk.com/forum/flying-blue-air-france-klm-other-partners/1436214-missed-segment-new-award-booking.html

Oops, no edit function. Grrrr.
I should have said miss the last segment if you have booked the same return journey.