I think best thing to do is just set off 30/45 minutes earlier than normal rather than try to find alternative routes.
If you get there early, then that's more track time. I aim to leave Surrey around 0800, which I hope will get me to MK before 1000.
As Humps said, I don't remember there being too many hassles getting to MK last year, but it was a nightmare getting home (left about 1700 and didn't get home until after 2000).