Wind can be thought of as the 'fuel' that wind turbines use to generate electricity. It is a free, theoretically inexhaustible fuel, although the infrastructure to turn the raw energy into useable electricity can be expensive. Wind does not have to be imported, so the UK's supply of it cannot be affected by international market forces or geopolitical disturbances.
However, the wind does not blow constantly and so it is possible for the supply of wind to the UK's wind turbines to be interrupted. This is due to its inherent intermittency as an energy source, which is a reliability issue.
These are the security of supply challenges facing wind. Read about the possible solutions.