Even though snus is a highly sought after product, it's illegal to distribute outside Sweden due to tobacco regulations. Ordering larger quantities has a high risk of getting seized in the customs as importing snus and other tobacco products are only meant for personal use. As much of the shipping is done under the radar, many products that are sold are even fake and contains illicit ingredients not meant for consumption.
The best way of securing your snus delivery is by befriending a Swede or by asking one of the many ex-pats groups (such as LondonSwedes) if someone is willing to bring a couple of cans from overseas.
There are some Swedish shops and bars in central London which keeps a small stock of snus under the counter. With some small investigation you'll be able to find these hidden hotspots.
If you opt for nicotine pouches and place your order from Haypp before 6.30 pm, your parcel will arrive in the UK the next day. It's then distributed with RoyalMail within 1-2 days depending on where you live.
If you simply can't wait for your online delivery there are several vape-shops in London which sell brands such as Lyft, Zyn and WhiteFox! The supplies are often limited and few flavors to choose from.