Carver said:
The 3000mm relates to the hydrostatic head (how rain resistant it is) and this one is regarded as being able to withstand extreme conditions and suitable for year round camping. If you are only camping in summer you can get a cheaper bigger one rated at 2000mm (don't go under that as the 1500mm ones are only shower resistant). That's a good price and will be good quality material but it's quite heavy at 18Kg. The 4 person size is for 4 slim average height people. If you are over 6ft you'll take more than 1 space up.
PS that's a great offer from Bluebee2, large tent and great for a family and plenty of space to store stuff until you learn to go with the minimum of stuff. If you don't like camping you should be able to sell it for the same price.
Even when well used to camping and knowing exactly what you need, extra space is always welcome, especialy when it rains (even more so if you have "mini people" with you).
If I am going for anything longer than one night, I will usually have two tables (one for the stove, one to play cards on of an evening while enjoying a beer or 7), said two ring burner with grill (even though the grill is very poor), a folding chair each, a couple of inflatable mattresses, often a portable heater (stops the woman from moaning for the wrong reason), cool box (for breakfast foods etc), cool bag for beers and mixers, cooking utensils, at least a 5 litre water carrier, etc etc, all takes up space, oh, and a variety of clothes, depending on the weather, time of year etc, gas cannister (& a spare if a longer trip), and three battery lamps (with spare batteries).
But it is great to spend a few days in the "outdoors" and if the site is right leads to happy and contented kids tired out by the end of the day.
P.S. also try and pack a trowel of folding shovel in case of serious heavy rainfall, nought worse than being flooded out)