The first thing you need to keep in mind is the situation of your separation. If the separation is happening because of you, you need to think twice before taking this step. If you are the sole reason for all the mess, it would be better for you to stay home and let time pass.
However, if your wife is the reason for the separation, you are more than free to see other people. If your partner has cheated on you, there is no use waiting for her to come back to you so it would be better for you to take a bold decision and move on.
Even if you have the license to date, you cannot expect to go out there and succeed. The world changes on a regular basis. Rules of dating are not what they were back in your time. You need to learn before asking someone out.
It would be a good idea to have a wing-man with you when you decide to hit the bar. Separation can be devastating and no matter how strong you are, in the dim lights of a night club with drinks and smoke, you can easily forget yourself. So it would be better to take a friend of same gender with you.