Now I know I cant afford to keep this plan so I haven't sent the money back yet. Once I covert the plan to permanent life insurance will I be able cash in this policy immediately?
No, there won't be any "cash value" for maybe five years. And yous "cash" is based on a small amount of what you've paid into the life insurance policy, not the death benefit.
Here's how you can learn more about convertible term life insurance and how it works.