Where can I buy a new logicboard fuse?

My mother-in-law's iPhone has stopped charging. After changing both the battery and the charge port, it still will not charge.

I have tested the fuse and it is indeed the problem. I am capable of replacing the fuse (my dad's an electrical engineer and through spending time with him have become quite accomplished with a soldering iron). My only problem is, where can I purchase a new fuse? I am in the UK.

I am aware that this isn't the easiest part to replace.

Many thanks in advance,

Ryan