There are many databases in the Libraries that may be useful for obtaining economic forecasts:
EMIS Intelligence includes a section under 'Countries' for 'Macroeconomic Statistics and Forecasts'. Forecasts usually extend four years into the future.
The Fitch Connect database is mainly focused on risk analysis, but part of their risk analysis for countries includes economic risk analysis (which includes forecast data).
The MarketLine database includes 'Macroeconomic Outlook' reports by country, which are generally built around a PESTLE analysis, which almost always includes some economic figures forecasted out at least a year or two.
The discussion in the 'Economy, Finance and Trade' reports in the Passport database generally includes some discussion of forecasted figures.