Really need to sort this :-)
Why can't you bleed the radiator? Do you have a radiator key? Is the valve stuck or missing? If so, it really needs fixed. The valve is also a safety thing. Bleeding the boiler will remove trapped air from the system overall and should help. But then, when it's fired back up, all the radiators should also be bled. As to the automatic refill, it depends on the system. Look at the inlet water pipe (usually directly above the boiler) and see whether the valve is opened or closed. If it's already opened, the system should refill automatically after bleeding. If the valve is closed, you'll have to manually open it to refill the boiler, then close it again when the boiler is filled.
