The UK gives hardly any aid at all to the whole of Pacific region. For example, in the most recent year for which full figures are available (2016), the UK gave £2.86bn to African countries and £2.34bn to Asian ones. The entire spend in the Pacific region was just £0.06bn with, as far as I can tell, none of that going to PNG.
PNG's largest aid contributor is, by far, Australia, providing US$7.7bn over a ten year period. The next largest contributor, providing US$1.7bn over the same period, is China.