I have a feeling you need to move on to a different recipe!
The only substitution I ever heard anyone using for sweetened condensed milk is equal parts of evaporated milk (or powdered milk and hot water) and sugar heated until dissolved. I have heard of people substituting half and half for evaporated milk so it is possible you could use it.
I think substituting anything else besides cream for the all purpose cream would dramatically change the recipe depending upon how much of that ingredient you need. I have ruined many recipes by substituting different diary products for heavy cream, whip cream, yogurt, etc. You may be able to find an all purpose cream recipe online you could use if you had milk, sugar, eggs, flour, butter, on hand.
I have heard of some substitutions for graham cracker crust-- one person I know used 1 part sugar, 2 parts melted butter with 16 parts crushed cornflake cereal. It was for a pie and I didn't notice it wasn't a graham cracker crust.
My general cooking rule is to make only 1 substitution if I need to. I have ruined a lot of dishes attempting to substitute too many ingredients.