If shipping tobacco, FedEx will not accept the package for shipping if the contents are declared - which they require - as pipe tobacco unless you have a tobacco license. UPS also will not ship pipe tobacco unless you have a tobacco license. The caveat with UPS is they are franchised and a lot of the owners don't give a hoot about the national UPS policy because they want to make money and will ship anyway.
If under 4 pounds, you can ship to the UK via USPS Priority International for about $66. I ship to the UK every week and have been doing so for many years using USPS and have never had a package lost. And they only ask if the contents are liquid, fragile, perishable or potentially hazardous. But you do have to declare what the contents are on the customs forms. You are okay with saying smoking pipes but for tobacco its best to say that you are shipping second hand collectible tins. That is a defensible position because that is exactly what they are.