Hi Georgie....I saw your posts in the Aussie thread. I'm in Qld. Anyway I thought I might see if I could help you a bit with your travel concerns. I actually have both coeliac disease and IBS, which makes me a very worried traveller. I also can't have any dairy. Having said that, I've been overseas 3 times since being diagnosed: twice to Canada (where I was born) and once to Europe where my wife and I did a Royal Caribbean cruise with lots of day trips.
Air travel has been discussed in other threads but I will add my two cents: some airlines are better than others. Japan airlines was excellent for example, while Qantas has never been that great (surprisingly perhaps). If I were to go to Europe again, I'd go Singapore Air (to try), but recommend Japan airlines with a free overnight stopover in Narita (a very nice old Japanese town). Last time in Narita I had plain rice for breakfast. Always bring extra food (though you can't bring your own water anymore!). I've brought Orgran muffins I've made up, Sakata rice crackers, Mentos, Sweet Williams gluten-free and dairy free chocolate bars (Tangarine and rice bubbles). My tinned tuna was confiscated at customs in the US (as it had water in it) but you can still put it in your luggage. When travelling I also carry extra food in a separate piece of luggage and cut down my clothes. You never need all that you think you do, and you may need some food when you can't find anything somewhere.
I'd look at two options you may or may not have considered with a trip to Europe. In fact I have been looking at them myself as I hope to improve in health someday (soon?) so I can go back. In France you can rent gites (self-catering apartments) in many towns for as low as 400 euro a week (I also prefer the small medieval towns to the big bustling cities). If you bring some food you can use as basics (eg. Orgran pasta) you can add food from local vegetable and meat markets. That is, if you don't mind cooking yourself (which in the end is safest). Australia's Orgran and Dr. Scholls (sp?) are two brands that are in European pharmacies/stores over there. You can check with both companies to see if they stock things where you are going or even use the local tourist offices to find out by email before you go.
The second option is to find a place that actually caters for coeliacs. In France these tend to be chateaux which are expensive. In UK you can find B & Bs that cater. In Italy I found this guy who likes to cook and only cooks gluten free in his house as he has coeliac disease: this is his website: http://www.domusalessandra.com/english/welcome.htm It is on Lake Garda near Verona and also not far from Venice, which you mentioned as a possible destination. Northern Italy seems better suited to coeliacs because of the risottos.
I believe gluten free is SENZA GLUTINE in Italy and SANS GLUTINE in France.
Please do PM or email me when you get back from your trip so you can give me a run down on what you find so that I can possibly use what you learn in the future. Hope this helps.