Even though I'm gluten intolerant, am pescatarian and intolerant to tomatoes, I don't find eating out too difficult in the UK, as I eat white rice and white potatoes, and dairy. Thai and Japanese food (sushi) are good. Italian restaurants can be tricky but some risottos are fine for me. Simple pub grub such as a whole baked trout with chips (potato fries) and a side salad is ideal for me.
I usually have to make a few minor compromises with stuff I generally avoid, e.g. oils high in PUFA, fermented foods, cow's dairy (I'm mildly intolerant, but fine with goats and sheeps). I only eat out about 2-3 times a month. Hence it would be a different story if I had to eat out more often, e.g. lots of business trips.
It's much more difficult when I'm on holiday or travelling, especially as I walk a lot, so finding enough safe carbs can be tricky, and often ice-cream ends up being the best choice when I'm in Italy (it's a great excuse!). This year I'm going self-catering on the Mediterranean coast so I'll be able to enjoy fresh whole fish with potatoes and salads when I do eat out.
Dinner parties are a lot more tricky, though there's a welcome trend to cook various dishes mezze/tapas style nowadays to cater for different dietary requirements. Party food is easier when there's a spread of things to chose from, and I usually bring along something I can eat such as cold frittata and some olives, or cheese and pineapple on sticks.
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.