A radiator cold at the bottom but hot at the top almost always means sludge has settled inside, blocking water flow along the base. Cold at the top with a warm bottom means trapped air instead, and bleeding fixes that in minutes. Sludge needs flushing, either chemically or with a power flush.
A boiler losing pressure has lost water, through a leak in the system, a radiator bled recently, or a failed part inside the boiler. How fast pressure drops tells you which. A small drop over several months is normal settling. A drop every few days points to a leak worth tracing.
A boiler leaking water usually points to one of three things: pressure running too high, a worn seal or joint, or a failing part inside the casing. Switch the boiler off, turn off the water supply if you can reach the stopcock safely, keep water away from the electrics, then call a Gas Safe engineer.
Pressure is the single most common thing homeowners ring us about, and the fix is often a two minute job you can do yourself. Here is how to tell the difference between a normal reading, a slow leak, and a fault worth calling out.