For several years, I have used UPS, sending them via Mail Boxes Etc who seem to have offices in most UK towns & cities. They have never broken or lost anything. I deliver them to the local Mail Boxes Etc local office, and UPS collects from them the same day. Quickest delivery so far was Preston to Hongkong. Gave to Mail Boxes Etc on Monday, delivered on Wednesday midday Hongkong time! A UK delivery is about £25 for 10 Kilos.
By taking them in myself, I avoid being trapped in all day waiting for a collection, which can be anytime between 0900 and about 1900!
Bob