Thank you all.
I just bought a non-toyota version on ebay (just searched for "HB4/9006 female plug"). I'm sure it will work, but I still think it's strange no one sells the OEMs locally.
Regarding getting one from a donor car - I actually messaged a lot of ebay sellers that were breaking their cars, but I think this part is so small, they usually don't bother selling it/shipping it. Though, if you have any suggestions for scrap yards to visit in London next time I have an issue - I would appreciate it if you could share their names/addresses.