When I moved into a second hand property. I contacted the ESB and GAS company to take over the services in my name. The house had been previously rented.
The GAS had been switched off and they came out and switched it back on and set me up with an account. The ESB were due to do the same but thankfully I rang them and they updated my details.
Just call them up as soon as you can and it should be straightfoward. Unless of course there is a balance owing from the previous owners - that is usually the solicitors take care of, I believe.
MAJJ