Check the power adapter you have for your laptop. On the back it will tell you the power information, if under input it says (which it should) 110-240v
Then geuss what?
Youre good. Just buy a UK shaped plug to plug your adapter in to, and thus able to plug it into the wall. Thats all you need, no voltage converter needed because your power adapter for the laptop can handle the UK 240volts.
Worked fine for me while I was in the UK, both in Belfast and Cambridge, so no worries.