Britain’s economy will slam into reverse this year as the cost of living crisis hits households hard and will see the worst performance of all the advanced nations, the International Monetary Fund (IMF) has warned.In its latest update, the IMF downgraded its UK gross domestic product forecast once again, predicting a contraction of 0.6 per cent against the 0.3 per cent growth pencilled in last October. The forecast means Britain looks set to suffer more than most from soaring inflation and higher interest rates.