Ordering from Magnet Baron to the UK

I've decided to pre-order the Battalion Box. I've never painted a single mini, so I'm kinda off the deep end, but the knights look cool and I'd like to ally them with my Space Marine army (Which I'll build when 11th comes out)

After reading through the pinned beginners guide, I was wondering if there's a UK equivalent to Magnet Baron for their pre-made parts? Or would it actually be best doing it myself with N52 magnets and a dremel?

I am also quite interested in using parts from Taro's Modelmaker. Are the replacement arm joints and hip extensions worth it? I know I will be getting the Armiger Twin Head set, as I'm not a fan of the standard Armiger heads.

Thanks in advance for the help. I'm aware I'm adding to the mass amount of question posts.