Today (8 October) the UK’s Department for International Trade published the provisional import duty rates (MFN) that it will apply on products from the EU in case the UK leaves the EU without a Withdrawal Agreement on 31 October 2019. For the complete list of products and duties (also other product groups than oils and fats) that UK's Department for International Trade published this morning, click. If your goods are not listed, you will not have to pay customs duty (tariff) when importing them into the UK.
Most oils and fats will be duty free, but certain oils, fats and associated products will face an import duty. The UK will maintain import duties on crude palm oil and crude coconut and palm kernel oil for food applications.
It will also apply import duties on UCO’s (heading 1518.0095) and other inedible animal and vegetable oils and fats classified in HS heading 1518.
According to this provisional list the UK will also apply duties on certain subheadings of HS heading 3826 (biodiesel/FAMAE) and HS 1516.2098 (chemically modified vegetable fats) but the exact description and scope for these products are far from clear.