It's ghastly, isn't it? Only after DS had lavish D&V when 2.5 and we ended up in A&E to get him rehydrated did we come up with some good ways of dealing with it:
(1) Have a bucket/bin/bowl ready by the loo so D can go in loo and V in bucket, as they often come together.
(2) Have a bowl nearby wherever you are for the first day.
(3) Clean up with paper towels, then disinfect all surfaces with Dettol spray or similar. Wash your own hands thoroughly. Don't try to clean up vom with reuseable cloths. It's gross, takes longer, and then you've got to deal with the cloth/water.
(4) A tip gleaned from Mnet years ago: if sheets are soiled, scrape off the sick into the loo before putting the sheet in the washer, or you'll end up with a machine full of clean sick.
(5) Don't try to rehydrate with too much liquid too quickly, or it'll all come straight back out. Try 5ml every 5mins and it's more likely to stay in. If you don't have Dioralyte, try 1:5 diluted apple juice.
(6) Live off ricecakes, plain crackers, unbuttered toast with perhaps a little marmite, diluted apple juice, and bananas (if you can stomach the smell) for a few days while your stomach calms down. NICE guidelines currently say don't cut milk for young children, but while I imagine this is true for bf infants, ime with DS he only gets better from D&V after a few days without milk; he at least seems to find it hard to digest (incidentally the A&E doc agreed, at least for a child his age). Better a few days on a less nutritious diet that stays in, than milk that comes straight back out.
God I hope we don't get it this time round. Good luck to all who do.