2 days in Belfast and 2 days in Dublin, when you figure getting to/from/between the two is not enough. You’ll get to see a bit of 2 big cities but only “experience” what’s really Ireland through the train window.

I would cut Freiburg or Paris and concentrate on the British isles with a side trip (probably by air since you don’t include London in your itinerary) to Paris or Frieburg.

A Britrail pass or a Britain/Ireland pass may save money. Try pricing your train tickets in UK at national rail. You can find a link in the “national rail links” sticky at the top of the “Transport” forum or under “transportation” on the “travel tips“tab. You may want to look into flying between Scotland and Ireland. It may end up being faster and cheaper than train/ferry/train.

Couple of things:
1) Why no London? Cut away Freiburg, and spend 3-4 days in London.
2) I would cut Inverness and instead go on a tour of the Highlands.
3) You’re really missing out on Ireland, try to cut a day from either Belfast or Dublin and go on a tour of the Irish countryside, I went to the Cliffs of Mohr out of Dublin and it was amazing.
4) I would advise some time in Glasgow and maybe a bit more time in Edinburgh.