turn off the water main at the stop cock. Turn off the electricity. rescue important papers and photos, take somewhere else to spread out and dry
you can buy or hire a wet-and-dry vac, it will suck up surface water off the floors and out of the carpets (carpets will need multiple goes)
open doors and windows, don't try to dry it out by heat and closed doors, this will just make it stink.
open the loft hatch to get airflow
put damaged stuff outside with a polytarp. Assuming you actually do have insurance cover, they will want to see what was damaged. Start writing lists of what was damaged. Even your list of persil/biscuits/flour will add up to hundreds of pounds when you have to buy new.
You will need big industrial dehumidifiers. The insurance company will (should) put a claims handler on who knows where to get them. Read the electricity meter before they arrive as they will use hundreds of pounds worth of electricity that you can claim for. You will also need an electrician to say if it is safe to turn the power back on. Make sure the house was not unoccupied for a month, and the heating was left on low, or the insurers will not cover it.
Book into a local travellodge or something until the house is habitable.