London, Edinburgh, Dublin

Do the first one, so you're not backtracking to Britain, then fly from Dublin to Paris. You might be able fly from Edinburgh to Dublin cheaply, also; see www.skyscanner.com. If you can book the London-Edinburgh train tickets soon, you'll get a better price on them; see www.nationalrail.co.uk.

As stated, do the first itinerary.

To save some time, you could take the Caledonian Sleeper between London and Edinburgh. It leaves London just before midnight and gets into Edinburgh the next morning.

Both Ryanair and Aer Lingus offer cheap flights from Edinburgh to Dublin. It's only a hour flight.

Aer Lingus and Air France have flights from Dublin to Paris.

I've recently been looking into all of these which is why I'm up to date on it.

Personally, I would scrap Dublin or Edinburgh, as you don't have time to cover both.

You will lose half a day travelling between each destination and you are proposing to travel during the school Easter holidays, so accommodation will be harder to find and more expensive. Assuming it is for this year and not next, you may struggle to find somewhere at this late stage. Cheap flights and cheap airfares should be booked 6 months and 12 weeks out respectively to get the best deals. Flying to Paris maybe cheaper than the Eurostar if you are travelling this month, not next year.

Hello Whitney & Taylor. You will have six days at the United Kingdom, after the day you arrive at an airport of London. I would stay in England those days. If you must go to Ireland, I recommend this travel plan :
Day 1 (the day after the day you arrive at an airport of London) : London.
Day 2 : London.
Day 3 : Fly from London to Dublin.
Day 4 : Ireland.
Day 5: Ireland.
Day 6: Ireland.
Fly from Dublin to Paris.