There are some manufacturers and retailers advertising memory foam mattresses in
the UK but I've heard that some offer obvious product details on their web sites (firmness, density, temperature-sensitivity, etc). This means that you have to make contact with them openly and ask for as many details as you can before purchase. The replies you get from them are a good way to determine how educated they are regarding the memory foam mattress types they hold and how much you can rely on their suggestions.