Customs might sting you but in theory there should be no charge if the goods are of less than £18 in value.
However the packet will have the dollar price and the post office are not that sharp and will sometimes charge you if is has a figure of more than 18. I have had some of the most fantastic incompetence from the post office and if you complain they stick their fingers in their ears and pretend they can't hear you.
The charge is a percentage but they also charge a set post office handling fee of £4.95 which was more than the customs charge on one packet I received, amazing. The guy on the complaints line didn't see a problem with charging me more to handle a fee than the fee itself :shock:
On the other hand I have got stuff before with no charge when it should have been quite a lot and then the post office is a fantastic British institution
Bill
PS apologies to any posties here you do a great job.