I'm planning a trip where I will be flying to Manchester on a transatlantic arriving at 9 am. I am heading to Edinburgh but was not sure how much time to leave between my arrival in Manchester & my departing flight to Edinburgh. Will 2 hours be enough for customs and possibly changing terminals? What about the rail?

Suz, have you booked this? Or can you book straight through? If not, look at going on by train.

There is a direct train from the airport to Edinburgh. It leaves at 11:27, arriving at 3:11. The train company will be Transpennine Express. Be sure to purchase your ticket ahead of time. This can be done using National rail enquiries. Good luck.

Since you're arriving at the airport, I'd fly on. Although there are different terminals it's not a big airport & you just walk between them. When are you travelling ?

www.nationalrail.co.uk for schedules and online purchases - cheaper tickets can't be changed usually i think so leave plenty of time between plane and train - fully flexible tickets are often absurdly high

PalenQ, try typing in what I suggested, (national rail enquiries) and see what comes up. I might be wrong, but it seems to be the same as what you suggested using.

Exactly the same, yes

i typed in National Rail Enquiries and the search box then changed to www.nationalrail.co.uk - so either works as they are the same

- the combined booking and schedule site representing all of the few dozen privatized rail franchises that formerly was British Rail

Visiting Edinburgh in July and checked rail options from London - costing us a family of 4 about 95 quid vs bmibaby of 99 pounds incl. taxes. Trip takes about 5 hrs from King Cross. But am told that the train is more scenic . Is that hype or the truth?

I personally always fly as I find it cheaper, quicker and more reliable. The part of the rail journey between Durham and Edinburgh is quite scenic but the rest is nothing special.

what may be nothing special to a U.K. resident whose been over it many times presumably could well be interesting to a foreigner - do you want to see airports or the lay of the land in between, granted south of Newcastle not all that great but still typical of England

Manchester Airport is a good one. I would stay with it, and use the plane. If you are a train buff, then go with the train. If not, the plane would be easier and possibly quicker, even with a two hour gap between getting off one and onto the other. (I'd prefer to make it three, just in case the luggage takes ages.)
National Rail is the place to go to look for the timetables.
TheTrainLine is where you buy them, but it makes you add on money for spurious insurance and even charges you for you to collect tickets at a machine! Avoid if you can, and buy tickets from the individual companies.
With that in mind, it would be less hassle to simply get on another plane.

One thing that surprised me is that the UK train fares are not as inexpensive as one would find on the continent. In making our plans we found flying to be a bit cheaper than taking the train.

I always find flying to London cheaper.

PalQ, I take you point about the land being more interesting to a non resident - but 250 miles of flat fields, housing estates, power stations and pylons ?

Nigello, the OP was asking about connections from Manchester a while ago & never came back to our suggestions. We are now discusing tongsa's London-Edinburgh journey - I think !