Agree with Moondog, couldn't have put it better myself!
DS started school today. School dinners £1.60 per day which sounds about standard. We are in Carmarthenshire, West Wales, and the school meals service was singled out as providing a good service by the Welsh Assembly Government long before Jamie's campaign (but good luck to him all the same - I think he should extend it to include hospitals as couldn't believe the dreadful tat I was served up after giving birth to DD recently....but that's another thread).
My SIL works locally as a school cook and she reassures my that at Primary level there is a hot meal and a pud each day, usually cooked on site, that are nutritionally balanced. Plus I have used some of her recipes for our meals at home (adapted to serve 4 rather than 150 obviously!) and they are great.
The younger children, such as DS, are served by the teachers or assistants and so get a proper combination of things on a plate (rather than the potential for just potato etc). They are allowed to go up to the "counter" to be served from yr 3 onwards, where there are additional choices of jacket potato or sandwiches, so I suppose there is potential for the pickier ones to get away with poor choices then.
DD is a good eater and generally eats whatever's on the plate. He would have a similar 2-course lunch at the day nursery he attended so he is used to having a hot meal in the middle of the day.
Think packed lunches would generally work out more expensive for me despite the various marvellously frugal costs quoted by some in this thread.
Am off to pick up DS now and see how the day went, plus ask what he had for dinner and if he ate it all of course!