Thanks to Hannah at KUTUU for the link to these inks that I'd never heard of , no need for white spririts or press wash, ink just cleans away with liquid handsoap and water. Theyre oil based and behave like traditional oil based ink and are available in a great range of colours transparent, semi opaque and opaque but also sell the basic CYMK for mixing your own which are transparent so you can over print layers of these inks to create new colours where the transparent coloured layers overlap. The only thing that worries me is cleaning wooden type with water, but great for linocuts and polymer plates but any worries email them and the'll resolve your questions. All the info on this product is here
You can buy online from Lawrence's and Intaglio Printmakers these links will take you the right page.