A quick shower down in the bath will be fine!
Wipe the chain with wet-wipes or a rag with a drop (and only a drop) of WD40 or GT85 (which smells nicer) on the rag, don't spray it on the chain. Wipe the crud off the chain/sprockets, then lube, wait, wipe.
The only real problem time is when the gritters have been out as salt can quickly corrode, a bit of raiwater and road-grime won't kill it immediately!