I have shipped several times to the UK. It usually costs about US $500 - $700 for permits, inspections, broker fees, freight, etc. So it is not worthwhile to do small shipments. Some of my UK customers also hired a broker to clear the shipment for them, adding to the cost.
Part of the problem is government requirements, and part is that few airlines will take animal shipments anymore. And British Airways, which still takes them and does go to Heathrow, is one of the most expensive. Some of the cheaper choices, such as Delta, go to Gatwick, and the shipment has to be sent to Heathrow. So sometimes it doesn't get there in time for inspection before the end of the day. So Delta often will not accept animal shipments to London. It can be a real pain to get it all done.
Shipping to other EU capital cities can be cheaper if they are served by Delta or other carriers that will accept animals.
If you will want to ship a large number of specialty corns, it is best to plan on doing it during the summer, maybe making a deposit the winter or spring before. Although there are plenty of corns around in the winter, the selection is considerably less than in the summer and fall.