From memory ParcelFarce ‘handling’ charge is £12, over and above any tax and duties owed. Dependent on the size of the item it seems that you might get Royal Mail, or you get Parcel Force for delivery. RM, I think, charge less and typically the item gets to your local PO, and then you get a card requesting settlement of charges. ParcelFarce, it goes to the central hub and then the paper slip gets issued.
eBay GSP from the US, at least in my experience, is horrendously slow – you do pre-pay the tax etc but the shipping takes multiples of the time it takes if the seller just ships via USPS or courier.
I have a real issue with the £12 charge as fundamentally I fail to see how they get to insert themselves into the contract between the buyer, and the seller’s obligation to deliver the item – the contract is between the seller and the postal service(s) – or so you’d think. It’s also far from a true reflection of the costs incurred by PF in processing the item. Again, from memory I think there may be some court cases pending regarding the legality of these charges…