Hi Graham,
In short no to the rotovator, for 2 reasons, 1 it will bring up the heavy clay to the top and smother the seeds and 2 grass needs a shallow seed be to form. its best to use a drill or over seeder unit such as the opico one combined with a spring tined harrow then roll.
I have been busy for one customer over the weekend repairing a padock that had been badly poached last year, they just got me to do the harrowing and rolling and they hand cast the seed to save cost. Simples!
If you need any more info just ask.
Alasdair