Connecting multiple loads to an extension cord
Look at the nameplates of all the loads in question -- they should list current.  Add up the currents -- if it's less than 15A, then as far as the circuit goes, you're OK.  The more that it's less than 15A, the more OK you are.
At least in the US, extension cords can be rated for less than the current of the outlet they're plugged into.  This can cause problems.
The safe thing to do is to check the extension cord &amp; see if it's rated (in the US, if it's new, there'll be a tag), then make sure you're not pulling more than it's rated for.  Better yet would be to run a second extension cord from that outlet to power your bench.  Extension cords cost a lot less than houses.
I'm the sort who regularly concerns my family and friends with my safety practices, so if I were at less than 15A of the circuit but suspect the extension cord of being on the edge of suitability, I'd go ahead and use it.  But I'd plug everything in and check the extension cord for heating (just hold it in your hand, or coil up some of it tight and hold that in your hand).  I'd also inspect the thing for wear.