Detergent
Several brands offer eco options (Ecover, BioD).
Avoid plastic containers.
If you wash silver, avoid all sodium (citrate, carbonate, bicarbonate) as they might be too harsh, use Bio D dishwasher powder instead.
Rinse liquid
Just use white vinegar. Buy it in bulk at the Source, or in 5L container on Ocado (you will need this amount if using other DIY recipes!)