A popular London wine merchant became the latest business last month to start stockpiling in case Britain splits from the European Union without a deal in March.
The possibility of Britain breaking off from its main trading partner without any arrangements in place will grow if the UK parliament rejects the draft withdrawal agreement on Tuesday.
Doom-and-gloom predictions about life after a "no-deal" Brexit are plentiful and highly politically charged.
The truth is no one really knows what will happen because Britain is the first to leave the bloc.
But here are some things London is telling Britons to brace for in the first days of a worst-case scenario pullout.
- Rip-off roaming -
We check our mobiles incessantly and this is where people could notice things first.
Free roaming would no longer apply and UK mobile phone operators can start charging extra for subscribers who pop off to "the Continent".
London is also urging people in Northern Ireland to watch out for "inadvertent roaming" when straying too close to the EU border with Ireland.
- Grounded at Heathrow -
Heathrow and other big airports can be a nightmare at the best of times.
But planes getting grounded when Brexit strikes at 2300 GMT on March 29 because airlines lose their licences would create chaos that ripples across the world.
London says it would "envisage" granting European carriers special permission to keep flying -- and that it would "expect" the 27 EU countries to do the same.
- Forms, forms, forms -
Prepare to start signing your name. A lot.
Thousands of companies that do business with Europe would have to fill out reams of customs and duties declarations.
Tourists who want to rent a car may need to get international driving permits because their UK licences become invalid.
And even pets might need to jump through new administrative hoops that require them to have new passports.
People might want to check theirs as well. Those that expire within six months of travel might need to be renewed in advance.
- Drug dilemma -
Things turn more serious for those who rely on medication.
Officials are talking to drug companies about creating a six-week "buffer stock" on top of the three months they already have in place.
This should help cover any short-term disruptions at the border. Britain will also waive the need for EU firms to re-test their drugs under new rules.
- Shoppers beware -
That one-click purchase at your favourite online store might start looking slightly less tempting.
The government says "increased costs and slower processing times" for payments made in euros are a possibility.
Parcel deliveries could get more expensive because waivers for certain import and sales taxes would expire.
- Flicks and tunes -
Catching up on the latest Netflix releases while coasting on a high-speed Eurostar train may suddenly become a whole lot harder.
Britons could theoretically lose access to streaming services while abroad -- everything from Spotify to Amazon Prime -- because the UK would no longer be in Europe's "digital single market".
And the Eurostar service itself might be in trouble because old licenses of UK train operators in Europe will be invalid.
- Pork pies -
Britons are proud of their Stilton cheese and Scotch whisky.
But the status of everything from Cornish pasties to Melton Mowbray pork pies will be up in the air because they will lose their "geographical indication" status in Europe.
Britain's 86 GI-protected products make up a quarter all its food and drink exports.
- Surprises -
A host of other industries and products could also be affected.
Britain will have to come up with its own warning stickers for packs of cigarettes because the current ones are protected by the EU image library.
Imported sperm donations could face delays or stoppages.
Caviar supplies might start running out because Britain will not be able to trade in goods covered by European endangered species rules.
Also facing possible disruption: breeders of pedigree British horses and sheep.