The dates on the home page back you up sinisterdexter:
Practice Week: May 30 - June 05 Race Week: June 06 - June 12

As you say, it will be a problem for teams as they will want come over at least the day before the competition starts.

Methinks someone forgot about TT when they put in the bid to host. It doesn't surprise me one iota. It happens here every time Norwich play at home yet people still expect to drive past the stadium on matchdays at final whistle, even though the roads get closed (with advance warning notices too) and have done for several years.