this 40k inclusive of all? dont they provide schooling for ur children? flight ticket for all and any other benefits?

Education is expensive depends on which school u get them, 16k a villa is an easy go. car- yes 2k+ depends on what u want,eg suv 4x4,prado,hummer. if its new maintenance will be covered for 3- 4 yrs. if its old its unpredictable. food cost and cloths based on ur likes..
internet depends on data speed, utilities for a family might be 500qr min depends how u use. if u r a brit, or any other european comparing with qatar is hope less. yes they have malls, they have deserts. they have all types of houses, cant be extremely hot to mild winter. if u go for life style just forget it for couple of years. if u go for more money. endure all unpleasant things come across and enjoy just diffrenec the host country offered u in comparison to ur home country.

40k is a very good deal but again it depends on ur past experience and income to judge whether its fair.i dont think u save much if u really live ur life style unless u deprive urself on things u find it ridiculously expensive. its best if your wife too could find work just to supplement if she likes then it will offload half of ur reflex actions on ur head :).

qatar has a nonsense Noc system which ties u to the employer.in the worse scenario, if inflation is too bad then it will take a toll on ur take home pay. qatar has the highest inflation rate in GCC. Dont over spend beyond ur limit.even if the loan is intrest free.imagine what happen when dubai meltdown seen in 2008. expats just dump cars houses and run to there home land.but qatar wont let u go without paying back.. just plan ahead because u have kids and wife to look back. its not a discouragement but just keep this mind too.. god bless regards