I would like to set up a new shipping option that places an "estimated" cost of shipping into an order as it checks out based on a table rate but with a note to the customer that "your shipping rate will be confirmed before dispatch".

Our delivery area is vast and our product range has a large variety of sizes and weights. It is too difficult to place an accurate shipping charge into our orders so we need the ability to get a firm carrier quote and then advise this to the client prior to shipping.