Tap hole for ceramic sink

I'm looking to buy a CERAMIC sink (Reginox RL301CW). The tap hole is semi drilled. I'm buying off t'internet and one site states that you just need to knock through from the centre punched point and the other is saying I'll need a diamond core cutter to do it but they can do it for £30 (they also wan £24 p&p) as opposed to free P&P at the other place.
I don't mind paying the £30 if theres a chance I could crack the whole thing, but is this likely if I'm careful and don't go at it hell for leather.

If your not confident or done it before, go for the £30 charge or find a sink pre-drilled.

I looked on 3 web sites that sell this sink and they all say to knock the hole through. I think the company who says you need to drill it are just saying that so they can offer to do it for £30. If you are not confident about knocking it through then call the company first, they have a web site, and ask them if it is an easy task.

I fitted my own ceramic sink recently and I was a bit unsure myself but the hole was precut so I went for the centre punch method...... Success