Asking if England is "mostly hot or cold" misses the nuance of its temperate maritime climate. Thanks to the moderating influence of the surrounding seas and the North Atlantic Drift (an extension of the Gulf Stream), England avoids the temperature extremes found in continental interiors at similar latitudes. The result is a climate defined by mildness and variability rather than intense heat or bitter cold.
Rain is a year-round companion. The west and north** (Lake District, Cornwall, Wales) receive significantly more precipitation than the **east and southeast** (East Anglia, London, Kent), which lie in the rain shadow of the western hills. This east-west divide is the single biggest climatic differentiator within England.
In summary: Pack layers and a waterproof jacket regardless of the season. England rarely freezes hard or bakes severely, but it is rarely dry for long.