In reply to Dandan:
I used seed on about 120+m2, up a hill. I had already rotovated it down to about 30cm to remove tree roots and the like. I got seeds from Boston Seeds, shady lawn type, although only a bit is in shade for part of the day. It takes about 2 weeks to start looking like a lawn and a month or so and its like its been there for ever. (I kept some seed back to go over any areas that were patchy.)
I also got some wild flower seeds and sprinkled them in with the mix. I was expecting a colourful lawn, but I've got bunches of smaller green plants growing in the lawn and some flowers, rather than the riot of colour I was expecting. If you want that sort of thing, you may be better with flower plugs / bulbs, rather than seed
As for the birds eating it, I don't really care. I put food out for the birds anyway, and it wasn't really a problem. You rake the seeds in after sewing anyway, so the majority of them are covered.