No, you do not need a hot water tank with an electric boiler in the UK. Electric boilers can heat water directly, so there is no need for a hot water tank. This can save space and money, as hot water tanks can be bulky and expensive to install. However, there are some situations where you may want to have a hot water tank with an electric boiler. For example, if you have a large family or if you use a lot of hot water, you may find that an electric boiler cannot keep up with demand. In this case, a hot water tank can provide additional hot water storage. Ultimately, the decision of whether or not to have a hot water tank with an electric boiler is up to you. If you are looking for a space-saving and energy-efficient option, then an electric boiler without a hot water tank is a good choice. However, if you have a large family or use a lot of hot water, you may want to consider having a hot water tank as well.