
Hello! I have indeed, several times. And I remember messaging you

It's not as daunting as it appears!
Obviously, do check to see if anything has been updated, as it's a few years since my last one. But the process runs thus:
1) Order the fedex pickup. You can only order a max of 24 hours in advance and the sample will be sat for less time if they go at the start of the week. But it can go over the weekend if needed.
Make sure you tell them to send an air waybill with the driver as you can't download one. Double check with them what additional forms you need for serum only - I think there was only one last time I did it.
2) Packaging. I find a posting box, about 8-10" long does the job. Second size up, I think. And bubble wrap. You want a little room to wrap the samples so they don't move, but not so much you're in danger of looking like an Amazon wannabe!
3) On the first day, get your samples. Give the Hemopet instructions to the vet. They can sit in the fridge overnight.
4) Also on the first day, so you're not rushing, get your customs letters done - there is wording for that in the instructions somewhere. 2 or 3 copies to be safe.
5) On pickup day, pack your box. Remember to pop a copy of the Hemopet order form in the box for ID. And make sure your form for customs is done. Write on the box something along the lines of "canine serum samples for diagnostic purposes only". There should be wording for this also on Hemopet.
6) Wait for Fedex! And don't forget the air waybill - the driver might not remember and you'll need to fill it in while they're there.
Fedex is your only option for this - there aren't any other couriers that I know of that will fly serum samples abroad. I used the Priority service if I remember rightly, cost around £60.