Read the reviews on here - https://www.masterofmalt.com/country-style/scotch/single-malt-whisky/ - you'll soon see that there's a lot of pretentious rubbish spouted about malt whisky, and opinions on each can differ wildly. So unless you know his favourite style just pick one from those recommended on this thread - even if it isn't his style if he likes whisky he'll still like it.
If you're ever in York there's a Whisky shop next to the Yorvik museum that stocks 100s of different malts rather than blends. I like a smoky smooth whisky. They'll point out whatever type tickles your fancy.
Thanks to everyone who took the time to reply, going to have a look at the ones he's got and use the recommendations on here to get something along those lines. Cheers all
Look to see if he likes the peaty/ smokey flavour, if so an Islay distiller May be a good shout. Otherwise steer clear of anything that mentions peat. I love it, but my dad says it’s disgusting. A speyside Whisky usually has none of the smokiness or peaty taste, so is good to look for if not. Arbelour is particularly good. You should be looking at around a 12 year old whisky at that price. Generally the older, the better... and more expensive.
If you don't know whether he likes peaty ones or not you could go for a lightly-peated one like Bunnahabhain, 12 year one is only £36 from Amazon/ Waitrose.
Have you thought about getting him a nice glass instead? I've got 2 pairs from here: https://uk.norlanglass.com/ a set each of the clear and the matt black ones. Also got bought the tumbler for Xmas. Really nice looking objects. Even though it sounds like mumbo-jumbo on the website, I did a taste test with the Isle of Skye Talisker someone mentioned above, and they genuinely make a difference (I'm not a whisky expert btw!).
I got one of these. Really nice little glass https://www.spiritofyorkshire.com/shop-c2/gifts-c4/spirit-of-yorkshire-whisky-glass-p28
My lad spent some time in Scotland and macCallan 12 year old is what they told him to drink. Personally I also like singleton but that's usually around £30. If he doesn't like Islay whiskies don't get him one, they are an acquired taste, as is anything much above 40 percent.
Agree about the Islay Malts being peaty/smokey, the Bruichcladdich is an exception though, it's an Islay malt that isn't peated. It's a bit like an Highland Park, but with a stronger unpeated flavour if that makes sense.