If anyone has any need to send items from UK (or anywhere else I think), We can highly recommend 'Send My Bag' . https://www.sendmybag.com Recently one of our readers sent a 20kg box with them, and it arrived safe and in good condition just one week later.
You book online, they send tracking address labels; and they they pick up from any address you want. You can send a box, suitcase or etc, and there is a handy packing guide video on the website. It costs £40.00 for 20kg - more for express delivery, standard a was pretty quick. They seem to be very efficient, and even phoned to check the box had been received.