Forgiveness of sin is not striking a bargain with God in which the sinner theoretically might escape judgment by bidding with God for justification to escape the full penalty for sin. We are never in any position to be able to 'big up' our good deeds and minimise our peccadilloes. Justification is entirely a matter of being completely honest with God concerning our own spiritual condition. Forgivness for sin is entirely enabled by God's Grace toward us. If you know you're not 100% contrite you can't be respectful of God's Grace because you would think you had fooled God into forgiving you. It's not possible to do that. God does not threaten us sinners with hell anyway. Hell was made for the devil and his angels, not the human race. Anyone who winds up in hell has chosen that option rather than facing a Holy God face to face while yet remaining in rebellion with disdain for God's Grace. .
I don't know if "full contrition" is even possible for a human being to have. For contrition to be truly "full," I think one would need to be so completely sorry and repentant that committing the same sin again would be nearly impossible. As sinners saved by grace, most of the time we're feeling some measure of sorrow over our sins while simultaneously admitting that we are virtually incapable of not doing the same things again... and again. But upon reflection, I think you might have meant to distinguish between "perfect contrition" and "imperfect contrition." The RCC tends to define perfect contrition as that which is motivated by love for God, and imperfect contrition as that motivated by fear of hell. Anglicans don't (AFAIK) observe this type of rigid, formulaic distinction. The key element in any sort of contrition is faith: that is, the faith which God has placed in us, by which we trust in His mercy, forgiveness, and undeserved favor in spite of our natural proclivity to fall down in failure after failure. We trust in the full efficacy of the blood of Jesus shed by Him on the cross for our sakes, and we believe God's word that He (as Paul puts it) imputes to us His own perfect, impeccable righteousness (2 Cor. 5:21; Philip. 3:9). Not that this grace is a license to willfully keep sinning, but it should be of great comfort and assurance to any who worry about their salvation. So, yes, any contrition will do. But any contrition we have is like a soiled rag before our holy, perfect God. The thing we need to focus on is not how good our contrition is, but how good, loving and gracious God is!