Sky Sports Box Office have the exclusive rights to the broadcast so (unless you can find a late-night bar that's showing the fight) you can't watch it officially unless:
(a) you've already got Sky TV ; and
(b) you pay an additional £16.95 to do so.
Watching illegal streams of sports events is
highly risky and can do some VERY nasty things to your laptop:
http://www.bbc.co.uk/news/technology-35434765
However, if you're determined to try anyway, these links (which I've definitely NOT checked out myself!) might help:
https://kidizen.zendesk.com/hc/en-us/community/posts/204870933--Watch-Scott-Quigg-Carl-Frampton-Live-St-ream-Online-Boxing-27-02-2016