MORE than 800,000 families in Britain and Northern Ireland will be forced to spend half of their income on debt repayments by 2017 if interest rates rise by present predictions and household income is squeezed, according to new research. The study by the Resolution Foundation think tank analysed the effects on families if interest rates rise by the expected 1.9 per cent in four years. It found the UK could be left in a fragile position with a major surge in families with high debt levels.