Have Sky (standard, not plus and not HD) going into an upstairs room, need to move it downstairs to room below.

Its pretty easy to extend a standard Co-ax cable, but can you extend the satelite dish cable as easily?

Or do we need to get a man in and fit a new cable from the dish?

You need 2 screw on f connectors & an inline connector

Here

uplink, very helpful thanks a lot.

What he said. But if you are planning to get Plus or HD at some point, you could save work further down the line by getting a quad LNB (the sticky-out bit on the dish) fitted and two new runs of cable down the downstairs room. The upstairs one might come in handy later too.