@Salieri comes up trumps yet again. Interestingly, I must have done dozens of searches over the last 9 months of ownership and never stumbled across that site as a source of new parts.
Its Delticom, a huge german car parts/tyres seller and 123spareparts is their UK business unit. I guess they are not that well-known in the UK, but in Germany they are one of the "big players"
this might work , heat up the sump area with a heat gun , and freeze the nut with crc freeze spray . The difference in temp might be enough to break it loose
