In a sense, once you are ready to offer yourself once more to the church, you can celebrate this return at any time through the sacraments of Reconciliation (confession) and Eucharist (Holy Communion). Our journey of faith is a lifelong process, and there will always be more you can learn, new ways in which you can offer yourself in service.
In particular, prayer is the key to your final preparations. Just as Jesus prepared himself for what lay ahead in the garden of Gethsemane, so you can prayer, “Father, your will be done!” Prayer for the light of the Holy Spirit, so that you will be able to make a good and honest confession and be open to the graces which God wishes to offer you through the sacraments. Pray for the gifts of the Holy Spirit, perhaps, in particular, asking for courage at this time.
Remember that you need not be alone as you local parish priest is sure to want to help and put you in contact with others who will welcome and try to help you.