As Alan Shipman (OpenU) points out, in the end the UK economic malaise really centres on one problem - the inability to raise productivity.
Among the causes:
ineffective Govt. industrial policy (focussed as it is on financial services);
rubbish management (which I've posted on before) & unwillingness to invest in workers' skills or wellbeing;
oligopolies stifling competition alongside hopeless (captured) regulators;
inequality of 'rewards'.