i will be using it to create purchase orders also and i need to quote that number and that relates to the product so it possible i would like it to go into the field called batch Number
It makes little difference WHERE it is stored, as the Primary Key for the table, or in a redundant, "BatchNumber" field. Either can be included in the PO by adding it to the query which returns the records for the PO. Adding any sort of adornment, i.e. the human useful prefix, "PC0", does not change the underlying value and is purely "human eye friendly".
The reason I suggested a separate BatchNumber is that option allows you to avoid the problem of missing values that inevitably occur in AutoNumber fields. If you can account for all of your batches without worrying about that problem of gaps in the Batch Number, then there's no additional value added by that separate field.