Hi Dorothy,
The first place I would start your mattress research is post #1 here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and avoid the worst ones. Before you consider the Novaform I would consider some of the other options you have (which are linked in the same post) if you are looking at making an online memory foam purchase.
Some of the better local options or possibilities I’m aware of that are in reasonable driving distance are in the Washington DC list in post #2 here and in the Fredericksburg list in post #9 here.
Phoenix