Hello Martha! Glad you enjoyed the Humble by Nature smallholding course, and glad it gave you the confidence to get some pigs!
I've no idea why people bother tagging weaners before selling them - if they are under a year old, all they need is a temporary paint mark to move to the next holding.
I use Fearings metal tags - mainly because I get a discount with them as a member of the BPA. They work fine and are easy to apply. Mind you, I wouldn't recommend their plastic tags/taggers. They don't stay in very well and the taggers are a faff to use and the pigs often run off with them still attached.
Good luck with the abattoir. Do report back when you get your meat. And feel free to message me with queries - either through here or via my websites.
All the best,
Liz