After analyzing the bigger timeframe perspective of the GBPUSD, it seems that the market cycle for this pair is heading for a bullish trend. The Fed Interest Rate decision will determine the continuation of this trend, although it's more than likely that the Fed will maintain the current Interest Rate value until December 13th.
Utilizing the Fibonacci Retracement Levels, we can expect a downward correction in the following days, followed by a long-term continuation of the original bullish impulse. So, for Scalpers, it's recommended to put a Sell order after the Fed decision as the price will move towards 0.5 level, possibly reaching the 0.618. Nevertheless, I'd say it's a good idea to place a Buy order once it bounces back, from these same levels, for the longer pip ride.