If you know that you will be visiting a wake after work, do try to dress in muted colours and pieces that are suitable for the occasion. You may refer to the article above for tips on how to dress.
However, if your company provides a standard uniform, you can choose to change out of the uniform if it is not appropriate for the situation. But of course, you can also visit the wake in your uniform if you are unable to find an alternative clothing - because what matters most is your presence and care for the bereaved family.