Rynair

Here's a link to Ryanair's baggage page. It should answer most of your questions:

Ryanair's Baggage Questions

Be aware that Ryanair charges extra for everything. YOu migh also want to check out BMI. They offer inexpensive flights between LHR and DUB and offer a better baggage allowance.

BMI

Use the link provided to find out the exact details. But I want to say it is 15kg per bag into the hold and you are charged a fee for every bag. They will also get you on payments for using your credit card etc, etc, etc.

The bigger thing I will point out is that ryanair does not fly from LHR. You will need to go to Gatwick to catch a flight to Dublin

Of course you can look into an alternate carrier such as BMI etc as mentioned.

Ryanair flies to Dublin from Gatwick and Stansted. You would need to allow a MINIMUM of four hours (five would be safer) between your scheduled arrival at LHR and your scheduled departure from LGW. You would need to allow a MINIMUM of five hours (six would be safer) between your scheduled arrival at LHR and your scheduled departure from STN. While there are direct National Express coaches (buses) between the airports, they are subject to traffic delays and the fare is not cheap.

Save yourself time, money, and worry about missing your connection. Fly BMI from LHR to Dublin. Since you'll need to go through immigration/passport control, claim your luggage (if you end up having to check it), check in with BMI, and go through security, allow a MINIMUM of two hours (three would be safer) between your scheduled arrival at LHR and your BMI departure time.

Air Lingus also flies from Heathrow to Dublin. I flew it this summer, the day Pres. Bush was in London and Dublin and our flight was grounded for 5 hours before takeoff. Their luggage allowance is abysmal.

John, Thanks for including Aer Lingus. I was in the process of editing my note to include them when I saw yours.

For the record, I had excellent service on an Aer Lingus flight from Dublin to Nice three years ago.

i took the large rick steves bag and checked it and a backpack for carryon on the ryanair flight from london to dublin. they charged me for the checked bag because you can only take one carry on bag and there are wieght restrictions.

Thank you all very much for your thoughts. As a result of your input and further investigation, we have made a reservation with British Midlands to fly out of Heathrow to Dublin. It was very inexpensive and seemed like a much better option than Rynair. Thanks!

You will pay hefty charges for checking luggage..............the reality is.... when we went in May.........I just planned to spend the money and decided not to worry.........