becareful digger, especially if it's only 8 or 10mm pipework!
1As Mcp77 said, TWO spanners required, make sure that valve doesn't move when you crack it open.
2, if you can move the carpet (if it is carpet) do it! not worth the risk of sludge on the carpet
3, I always drain the rad before I lift it off, makes it a lot lighter and saves the panic of trying to flip it over with sludge dripping all over the place. just put a container under a valve when you crack it. If you crack the bleed valve be careful 'cos the water will gush out!
4, Thermostactic valves, some TRVs don't have an OFF as such, just a 'Frost' setting which means it is always open ever so slightly. In this case unscrew the cap from the valve (a knurled ring under the temp settings) make sure the TRV is unscrewed to highest temp and put a 5p coin inside then screw the cap back on. Then turn the cap as if you are turning the temp down and this should shut the valve off.
5, If it's a combi boiler, the system will have to be topped up when you put the rad back on. (A flexi feed tube near the boiler, Isolater valves at both ends) ,open both up until pressure reads 1 bar (or slightly over) bleed rad then top up again. A gravity fed system (An expansion tank in the loft) will fill itself!
best of luck mate
John
PS don't forget the 5p!!!!