All sorted. Got the oil nuts and half nuts on the spares scheme.
Suitable 1/4″ 26tpi nickel plated oil cups can be obtained from Harrison Lubrication Engineering Limited. Go to their website and type in oil cups in the search area. The various typs of cups that they supply will come up and select threaded oil cups and the size/thread required from the drop down section. I think that the model required is C1737.
Anyone found a good gearbox undertray that they want to sell?