LFA17, Lake District, Cumbria
Within the United Kingdom there are a number of military low level training areas. Cumbria is no exception and the area of the Lake District is well known for this type of activity given its varied and mountainous terrain. This area is referred to as LFA17 (Low Fly Area 17).
It should be noted that aircraft are by no means guaranteed on any given day. However, with determination and patience the rewards can be exceptional. Types of aircraft that may be seen in the area include, F-15E Eagle, Typhoon FGR4, Hawk T.2, Hercules and helicopters. Good luck!
At various points it is possible for aircraft to fly as low as 250ft at over 450 knots but in certain area's can go as low as 100ft. Viewing from South of Ullswater is one of those locations.