Another camping refusenik here. I went to Eurocamp a few years ago (in a static caravan chalet bungalow, which was just about acceptable) and the camping section of the camp was like Soweto. Miserable people crouched in the mud, cooking beans over little stoves, tents festooned with wet laundry...I imagine getting back home would have been more of a holiday.
But, yes, you are right, Beachy - a house in Cornwall for a week costs considerably more than £400. Although sharing a big house with another family brings the costs down a little.
We got back this afternoon, and have spent the evening de-sanding and unpacking. All in all, a lovely break. I'm back at work tomorrow (boo) leaving DH in charge at home, but he won't be bored; I've prepared him a nice To Do List. 
Lights were out in this house between 10pm and 11pm, in memory of my lovely grandpa, who survived the trenches, and lived to the grand age of 92. He had an impressive lump in his thigh (a bullet, which they left in), and we have an embroidered cushion cover which he sewed while convalescing from being shot. Can you imagine an 18yo man today whiling away his time in hospital with a spot of embroidery?