Heathrow is a disaster. You will spend half a day (an hour on the tube, there are quicker but more expensive ways) getting out of the place and into London :-)

Well, LHR makes sense if you're going to London. If you're going to Scotland then it makes *much* more sense to fly to a Scottish airport.

I would not say that LHR was a disaster but it is one of the, if not the busiest airports in the world. Glasgow on the other hand is a one terminal regional airport and hence very much less busy.

Obviously if your destination is in Scotland then it makes sense to fly there but you are going to have to transit through some other major airport anyway as there are no direct flights to Australia from GLA.

Therefore your choices are limited by the airlines that you can take and also on the price.

If you have to fly into LHR lets face it you are not gonnna die, it just might take more time to get out of the airport.

I would always try to use a regional airport if possible though.

"We are now considering starting our trip in Glasgow and working our way down. "

As Ronaldo says, you may not have much of a choice, if you can fly direct from Oz to Glasgow sure that would be preferable but I doubt you can :-) For example you may have to change at LHR in order to get a flight to Glasgow, in which case, changing planes at LHR is *probably* worse than just arriving and going into London. ("probably" because it depends which terminals you have to change between). I think therefore it depends very much on your flight plans plus you will in any case have to go through immigration and so all the time consuming stuff will happen whatever you do.

'We are now considering starting our trip in Glasgow and working our way down.'

Where else do you plan to visit, apart from Scotland?

'For example you may have to change at LHR in order to get a flight to Glasgow,'

Or you may be able to change at somewhere like Dubai or Singapore and fly from there to GLA, perhaps? Or you might consider Manchester, which has more intercontinental flights than Glasgow. It's certainly worth avoiding LHR is you can.

Or connect to Glasgow (or Edinburgh?) in Amsterdam or Charles de Gaulle

While "disaster" may be a little strong now the T5 chaos has subsided, it is by no stretch a "nice" airport

I always find the transfers in Amsterdam to be particularly hassle-free as you don't have to hop on and off shuttles in the switch over