Good, many of these tax credits do not achieve their stated goals and are simply windfalls for those is a position to use them. Every economist would agree that they are very poor tax policy. Also they are not controlled in the same manner as program spending -- proposing departments do not see their budgets reduced by the tax expenditure. 

Any revenues collected will either provide an opportunity to reduce general tax rates (or will serve to reduce the deficit).

BTW the Tories had their own approach to increasing revenues as they tended to expand what taxes apply to without touching rates.