Hi Gareth and Steve, thanks for the responses!
Gareth, yeah I've heard Febi is a good company. Unfortunately, I can't seem to find a knuckle from an aftermarket company which I have previously used or even heard of. I can only seem to find it from the place I linked or other companies on Autodoc which, like I mentioned, is only selling parts from manufacturers I have never come across before like Ridex.
Steve, I have looked at helicoiling on the forums, can't seem to find a definitive answer on whether it is safe. For day-to-day driving, I assume it is given your recommendation? There's a cheap one on eBay for £10-£15 unbranded (link). Again, I assume branding does not matter when it comes to this? Should threadlocker be used as well? In all honesty, as a new DIYer, I'm scared to helicoil myself just in case I don't drill square into the hole and then ruin the whole thread.