If I make a mistake with my packing - can I go into the bonded warehouse to fix ?

Unfortunately No. Bonded warehouses are storage facilities and by law are prohibited to allow packing (and other activities) inside the warehouse. Storage only.

As well as daily storage charges, goods that are put into, or removed from warehouses incur an in/out charge to cover forklift, labor, and administration costs.

If goods do need to be repacked they will have to be removed from the warehouse and will incur the above mentioned fees.

It's best not to remove goods from the warehouse after they have been stored prior to shipping.