When a warrant is issued for a person's arrest, they will be arrested and taken to jail if found by law enforcement (LE). The amount of time a person remains in jail on a charge will depend upon the terms for release set by the court, and the person's ability to meet those terms (usually, the person's ability to pay to get out on bond where the bond is secured by the court). I'd suggest you look into doing some community service asap so that you could at least show the court when brought to answer for the failure to complete it that you have taken steps to comply with the court's order. Depending upon the judge, the things happening in your personal life may not garner sympathy with the judge where you knew of your obligation to complete community service but did not do so. My strong suggestion would be to consult with an attorney about your matter for a more case specific evaluation. If you cannot afford to hire a private attorney, and if this is a DUI case, you have the right to request a court-appointed attorney.
If you cannot afford an attorney and you are facing jail time, an attorney may be appointed to represent you. I would at least consult with a local attorney. You may find that the advice you receive durning the consultation will help you determine how to proceed. Good luck.