Hi Neil, welcome to the Practical Caravan forum and website, and I hope that you will enjoy using this site to help you to make an informed choice when you buy your caravan.
The NEC exhibition is a great place to have a look around and to compare several different manufacturers and ranges and of course members of the Practical Caravan editorial team including Nigel Donnelly the magazine editor are often on hand to chat to and to offer their advice.
There are usually some very good deals to be had on new caravans at the NEC show but don't forget that if you decide to purchase your caravan from a dealer who is a long distance from where you live any warranty work that might be needed usually has to be carried out by this supplying dealership and this could involve a long round trip.
Before the show have a look around the forecourts of local caravan dealers to form an opinion on layouts and interiors that you and your family like, this is much easier to accomplish when it's quiet and not so crowded and you can then visit the NEC armed with an idea of what you are looking for.
Some local dealers are prepared to price match the NEC deals and obviously you should expect a discount for no part exchange and you could also negotiate for accessories such as a leisure battery, Aquaroll and perhaps an awning as part of the deal.
Good luck and enjoy choosing your caravan, please let us know how the search goes