If it was my house and it was looking likely to flood, I'd buy a roll of polythene and a few ton of bagged sand from builders merchant, wrap the building in cut strips of poly of abouut six feet with 4 feet up the walls, 2 lapped to ground and weighted with sand. Then dig a sump hole (ideally with a digger) at a low point of ground, hire a pump and hose from hire shop, then pump water to a lower point/ drain / river
You could do all that for a few hundred quid, but only if you're not the low point
Hope it doesn't come to that for you