It's easy to do, BUT you need a bit of thought and in particular think about the eventual situation you are aiming for.
And this starts right at the point of getting a quote for the new electricity connection.
You want to make it clear you want a "building supply" right from the start.
Then you have to provide a waterproof enclosure for the electricity company to fit the supply head and meter into. you can usually then fit in there a mini CU with RCD to feed a couple of sockets for site work, as already mentioned TT'd.
Now then. later on when the house is built you will need the supply moved over into the new house.
If you have done it properly and ordered it as a "building supply" then that should already have included the cost of moving the supply over to the house when you are ready.
The DNO here (SSE) are usually pretty good at free issuing a length of concentric incomer so you can feed that out of the house, and do the trenching ready for the DNO to come and joint it when ready to change over.
There is an alternative that I am doing and that is my supply in an outside meter box is staying there permanently, and i just have a submain from that to the house.