Hello Ann,
You may get all kinds of advice, but the most important thing to remember is that no one else has YOUR needs exactly, and what may be good for one person can be a nightmare for another.
Firstly, go on the web and order all the caravan brochures you like the look of. Whilst waiting for them to arive, write down exactly what you think you want, on a piece of paper.
When the brochures arrive, look through the specifications of the size van you want, and see if any match all your thoughts.
Now is the time to get out and about and go to as many dealers as you can and actually look at the vans, and see if they match your expectations.
One VERY important thing though, is to find out what your intended tow car is capable of towing,legally, as going for a bigger van may require a change of vehicle too.
As for buying, with a dealer at least you should get some kind of warranty on a secondhand van, you will get full warranty on a new van. Buying privately can be a shot in the dark, and risky if you dont know what to look for.
The main problems with private secondhand vans are: 1. Is it a stolen van? By checking the vans chasssis number with Cris you can find out(if its been registered).
2. Is there ANY sign of damp? a musty smell, or the owner having sprayed air freshener in the van just prior to your visit should ring alarm bells there.
3. Has it been serviced properly? do all the appliances work properly, are the tyres safe, how old are they?
There are lots of other things to ask or know what to look for, but this is a start.
Hope it helps you a bit.