Over a year ago my father made a big announcement at a family dinner: “I’m taking you all to London for Christmas!” He shared that spending a Dickensesque holiday with his kids and grandchildren was a longtime dream and he ordered us all to start shopping for flights. Who can argue with that? We were all elated. And so my husband and I and our two kids are flying into Heathrow mid-December and then we’ll meet my brother and parents at a house that we’ve rented. I’ve been nothing but excited but when earlier this month the U.S Department issues a Travel Alert warning U.S. citizens of “the potential for…