The big issue for the world I would see is the impact the famine had on British politics. It absolutely destroyed the whigs as a political force and put an end to their protectionist/laissez-faire economic policies, helping bring in the liberals.
Not landing such a blow on the whigs and things might work out rather differently.
Excuse me, but the Whigs were the Liberals. The Whigs were laissez-faire, but also Free Traders, which the Tories opposed. The PM, Sir Robert Peel, had become a Free Trader - but in breaking with Tory tradition he split his party and made way for a Whig ministry which lasted six years. Whig, Liberal, or Peelite PMs were in power for 18 of the next 20 years.