Adam, I bought my parts from eBay.
https://www.ebay.co.uk/itm/BMW-MINI-...8AAOSwBnZaoPQw
Is your pipe a one piece metal pipe or has it been changed to a steel braided hose previously? Like mentioned above, if it's leaking from the banjo bolt washer, then you should only have to change the copper washer.
But if you have a leak at the original pipe fitting on a MINI original pipe, then it is advised to upgrade to a similar hose to my eBay link. There are a few videos on YouTube also. One good one by Eric the Car Guy, American video but fittings are the same.
Here's the video link:
https://youtu.be/7MWiOnZxURw