In the grace of repentance, our soul is awakened to its wretched state before God. We recognize our need for a Savior, and by taking hold of Christ, we are empowered to turn from our sins, renounce the world, and bear our cross, undeterred by the scorn of others or the cost of discipleship.
Repentance unto life is an evangelical grace, the doctrine whereof is to be preached by every minister of the gospel, as well as that of faith in Christ. WCF 15.1
Repentance is the direct and immediate result of God’s work of regeneration in the heart (John 3:3; 3:5; Ezek 36).
Regeneration > Faith > Repentance
Repentance is not forsaking sin that you may turn to Christ, it is turning to Christ that you might forsake sin.
Is repentance necessary for salvation?
It depends on what you mean by repentance.
If you mean 1) that you must stop sinning before coming to Christ then obviously no. But if you mean 2) knowing you cannot save yourself, by grace, you turn from your sin and self-righteousness to trust in Christ alone to deliver you from it, then yes, it is necessary. No one can come to Christ unless they come to Him as the Savior from sin.