I had to have my blood cheacked for glucose at my booking in appointment because of my BMI. I was told that my blood would be checked again at 28 weeks because they had tested it at booking in. My booking in was fine but my 28 week was 6.4, 0.4 higher than they liked so had to go for GTT, everything was fine and the test is simple. If you need to have it you'll be told to fast from the a certain time the night before, then they check your blood before you eat or drink anything (water is fine) in the morning, then give you a glucose drink (in my case lucosade) then wait an hour or so and check your blood again.
They only check you if there is a family history, high BMI ,sugar in urine sample (I think on more than one occasion) or if a blood sample comes back high for sugar.
I wouldn't worry about it you don't sound like a candidate for one anyway :\)
There was a little girl, who had a little curl, right in the middle of her forehead. When she was good she was very, very good, but when she was bad she was horrid.