Joining a company it is very likely that your manager was aware of this condition and had passed this information on to others before hand so they are aware also. Potentially if you have a tic and you end up making eye contact with someone just mime sorry and smile and see what their reaction is.
If they smile back the likelihood is that they are aware and learn to put up with it. It is also very likely that it does bother people but if they understand and are aware of tourettes they will learn to live with it even if they are bothered as they know its not something you can particularly control.
If you approach them I'm sure they will be understanding and not assume you are insecure about it but just querying your thought but theres a large chance that people don't talk to you about it just incase you do infact feel insecure so if you openly discuss it to colleagues they'll likely be more understanding of you and your condition