Tubulars have a tube, but it's inside the casing, which is sewn together then glued to the rim. Most people who use tubulars carry a spare tire and install it when they get a flat. But, in that situation, since you're using old glue, you need to ride verrry carefully around corners, lest you roll the tire off the rim.
Frankly, they're a PITA for regular use. There are plenty of clincher rims and tires that give similar performance. Unless this is going to be a show bike, I wouldn't mess with tubulars.