Britons are being warned to brace for a 597-mile “wall of rain” expected to pour down across the UK next week. Forecasters predict that “widespread” rain and showers will hit Britain this weekend before a band of wet weather is set to stretch from Plymouth to Fort William in Scotland – around 597 miles. Downpours could see up to 6mm of rain fall per hour in south west England. Showers are expected to begin on Thursday with widespread rain affecting most of the UK. The huge storm cloud of wet and wintry conditions looks set to hit next Saturday, according to the latest weather maps. Wet conditi…