I have always preferred carpet in my lounge as I feel it is a lot comfier and warmer especially in winter and now that prices of fuel are rising so much I think it will be a lot warmer in a house with carpets than laminate. The main advantages to laminate is that children will have more difficulties damaging it and also it will be good for people who have many allergies especially so to dust mites. Children though will not find it as comfy when playing as they often sit on the floors. I am still happy with my carpet though.
So what's he doing with his money? Is he saving for his own place or is he blowing it on nights out, designer clothes etc? £40 wouldn't pay for much more than his food - it's a very paltry contribution towards gas, electricity, water rates, council tax, room rent, use of washing machine etc. If he has £300 a week disposable income, he should give you much more than that. I agree with magnius that you should work out the real cost with him, including a bit of rent for his room and ask for that amount. If you can't bear the thought of actually taking so much from him there's nothing to stop you keeping half in a separate account and presenting it back to him when he buys his first home. But if he thinks he can earn that sort of money and live at home for free, he's not living in the real world.