Thats shocking service Alison.
Bleeding a radiator is dead easy, all you need is a screwdriver, normaly a flat blade one and a cloth to catch drips.......you dont need the central heating on to do this.
At one end of the radiator on the top you will see a small valve, Ive attached a picture for you, all you do is slightly loosen the centre screw and you will hear air hissing out of the radiator, as soon as water starts to flow you tighten the screw, hey presto youve just bled your radiator.
If you system is sealed, most are, all that means is that you have to add water to the system yourself, you will find a pressure gauge and two taps under your boiler.........hopefully the installer told you about this/left an instruction book........you might have to open the taps to let a bit more water in..........on most systems you need to see a pressure of 1.5 bar.
Hope this helps!!
Regards all
John