London/Scotland/Ireland

Not all of it. Maybe some of the highlights.

I've probably spent three or four months in Scotland and haven't seen it all. I have no idea how many times I've been to London and there are still odd bits that I've missed. I've been to Ireland and going back for a month in a couple of weeks; I won't be able to see all I want to see.

Pick and choose; it's the best you can do. If I had three weeks, I'd give five days to London, a week to Scotland, and the balance to Ireland.

If you want to spend 5-6 days in each, yes. If you want to do more than London and a limited number of day trips to parts of England- you might need a bit more time. Here's one possible itenerary:
Day 1- travel from USA to London

Day 2-6 London with 1 or 2 day trips by train to any of following- Windsor, Stratford-upon-Avon, Cardiff Wales, Bath, Canterburry, Dover, Brighton, Winchester

Day 7 train to York- afternoon and overnight there

Day 8 train to Edinburgh

Day 9- Edinburgh

Day 10 Train to Inverness

Day 11-13 Inverness with day trips possible (Eliean Donnan Castle, Isle of Skye, Culloden and Clava Cairns, Great Glen, Glencoe, Loch Ness/Drumnadrochit, Orkney, etc.)

Day 14 Ferry or fly to Dublin

Day 15 Dublin- rent car

Day 16-20 Tour Ireland by car (Ring of Kerry, Killarny, County Cork,Cliffs of Mohr, etc. based on interests) end at Shannon

Day 21- fly to USA from Shannon

I am not as familar with Ireland as with Endland, Wales and Scotland, so that is why it is more vuage. I am certain others will chip in ideas.

If you want more in depth time, limit yourselves to London, Inverness or Edinburgh, and one place in Ireland (you could fly between using cheap airline) and do day trips out.

It all depends how you are planning to travel.

Public transport in London is easy depending how much you like big cities, 3-4 whole days no problem. Train from London to Edinburgh one day and two days there then rent a car for specific destinations.

You can ferry to Ireland and spend a week easily hitting other destinations.

They are quite big distances so get an idea of what you would like to see and how you would need to get there.

Yes, I think you can. First, fly to Shannon. Consult a map and lay out sort of a figure-8 driving tour, looping up to County Galway for Connemara and a day trip to the Aran Islands. (Galway is also good for shopping.) Next, loop down through the Burren, Cliffs of Moher, Tarbert ferry as a shortcut to Dingle, down to Kenmare which is a good base for the Beara and the Ring of Kerry. Reverse your loop if you prefer. Skip Dublin--you have better cities coming and your time is limited! Do the touristy but fun Bunratty Castle banquet either your first or last night. Suggested planning website: irelandexpert.com I know I will run out of room, so Scotland is in the next post.

Scotland / England segment: Good Scotland web-site is undiscoveredscotland.com Fly to Edinburgh, spending one full day there. Get rental car, head to Inverness. All day tour to the Orkneys if you are interested. See Culloden and Clava Cairns, Loch Ness, Skye, Wester Ross if time permits, Glencoe, head south-east to see the Border Abbeys, cross the border into England, see Lindisfarne (Holy Island), Alnwick Castle, Fountains Abbey, York. Return rental car at train station. Train to London. Enjoy London and day trips. You can reverse all this if you need to start in London. If possible, I would save London for the grand finale.