I have a very uneven lawn. Should I roll it, aerate it or what?

Don't roll it. This will compact the soil beneath the lawn. When you compact the soil you squeeze the oxygen out of the root zone of the lawn. The roots of grass plants, like the roots of all plants, require oxygen.

To level an uneven lawn: buy enough triple mix to fill in the valleys and even out the peaks in the lawn. After spreading the triple mix you will put down some Golfgreen grass seed. I recommend Golfgreen because it is the best quality lawn seed available. Buy quality grass seed for a quality lawn. Water it well until the seed germinates.

Now, you are not going to do any of these steps until the grass has dried out a little bit. It needs to be dry enough so that you can walk on the lawn without leaving a permanent impression with your shoe. That's my rule of thumb for determining when you can start to walk on the lawn, fertilize and begin to over-seed.