This could include the gbrf petroleum livery https://www.keymodelworld.com/article/exclusive-class-66-66794-petroleum-livery-oo and would include grain thamesport and maybe grain foster yeoman
It would probably be better to wait and see if passenger services get restored to the hoo peninsula. Although the plans seem to be on hold indefinitely at the moment. As it stands now, I think there's only a handful of freight services a week.
I live near there and there is still a decent amount of trains like we could do scenarios from grain now and not wait