Thanks CTG and Stiffy. They didn't say why I have to test before meald on the phone and I couldn't really discuss it in detail as DD was in need of my attention and we were also trying to get out the door. It is for the full pregnancy though, so I am going to discuss it with them next week. I asked on the Type 1 thread about it too and no one there seems to think this is normal. Odd, as I think our diabetes unit is meant to be very good. 
NewChoos, I think most people aren't that strict diet wise in pregnancy tbh. I know my friend said she would see people eating chocolate and drinking full sugar drinks in the waiting room in her first pregnancy. I was also super strict last time and although this time I wouldn't dream of eating a bar of chocolate, I've been having crisps as snacks and not been super strict. The same friend also told me she was eating her normal (goodness knows how she is so thin!) 4 bars of chocolate a day in her second GD pregnancy and openly told the diabetes team about it. She kept her levels down with brisk walks frequently throughout the day and a glass of red if they got a bit too high. She said the diabetes team were bemused to say the least, but appreciated her honesty. 
curiousgeorgie, my first two children were biggish and I was checked for GD in my second pregnancy as I had glucose in my urine several times. They said I didn't have it, but DS was born at 38 weeks exactly weighing spot on 10lb. Then, when I did have GD with DD and was insulin controlled, she was born at 37+6, so almost the same gestation as my DS, ut weighing 6lb 15oz, so a whole 3lbs less than DS! I think some babies are just destined to be big regardless.
roomforalittleone, I didn't have a clue with DD. I had already had 4 pregnancies without GD, no glucose in my urine, ever and just had the test as my BMI was 30
and DS2 had been 10lb. I didn't give it a second thought after having it, until my next appointment when I found i had it. I was borderline at diagnosis (24 weeks) but by 26 weeks I was on insulin as it was obvious I couldn't diet control and by the end I was on whacking amounts of insulin.