Most mortgage deals will require some level of deposit. The more deposit you have the cheaper the cost of borrowing the money. As a general rule you will need to provide a minimum of 20% of the property's value.
However, if you don't have a deposit or only a very small one, there may still be options available to you. For example, Aldermore's Family Guarantee Mortgage allows you to borrow up to 100% of the value of the property.