Of course, even airports that haven’t been directly affected will now face disruption and delays as a result of grounded planes elsewhere.
Network Rail is making extra seats available on trains to take the pressure off airports and help passengers making internal flights get around but for many people, travel plans are in disarray.
If you're affected, what are your rights? Bob Atkinson of travelsupermarket.com said: "With air travel plans in disarray, it is vital that all passengers travelling by air in the next few days are in contact with their airline, tour operator or travel provider before making their way to the airport."
When will the disruption end?
It's very hard to say; the situation is constantly changing and airports that are not affected directly are still facing problems. Airline staff and planes are not in the right position to run flights, adding to the delays.
People are being asked not to go to the airport if their flight has been cancelled but to contact their airline or travel agent and find out if their flight is going to go ahead or when they can be flown back.
Which airports are closed?
At the moment, all airports in Northern Ireland, Ronaldsway, Edinburgh, Aberdeen, Inverness and northern Scotland are closed. In addition, Cardiff, Swansea, Bristol and Farnborough airports are currently no-fly zones.
Other airports, including Birmingham, Norwich, East Midlands, Manchester, Liverpool and Leeds Bradford have reopened.
Can I get a refund?
Yes. If your flight is cancelled as a result of the ash cloud then the airline should reimburse you.
Passengers stuck overseas whose flights were cancelled and who made alternative arrangements to get home will also be due a full refund.
Of course, some people will still end up with extra expenses, because they have to put themselves up in hotels, while others will miss out on connecting flights, onward travel or booked hotel rooms and car hire arrangements.
Will the airline pay my costs?
If it cancels your journey for reasons beyond its control then the airline doesn't have to compensate you but it should meet your accomodation costs and pay for meals. However, some airlines are reluctant to pay out. You can read more about making a claim in our article 'How to reclaim volcano travel costs'.
Normally, delays result in compensation payouts from the airline; however, Bob explained this is not the case for today’s delay.
“There is no compensation due from airlines for delayed departures as the circumstances are beyond the reasonable control of the airlines and therefore EU rules on payouts do not apply.”
Will my insurer cover me?
If you have travel insurance, you may assume your holiday is protected but that's not necessarily the case. Your ticket price will be refunded by the airline but your additional costs may not be met by your insurance provider if you're not covered for natural disasters like this.
Some insurers are compensating people who have lost out because they cannot reach their destination and can't get a refund, for example, on hotel rooms or car hire. However, not all insurers will pick up the bill for costs incurred because you're stranded overseas and paying for a hotel and meals.
Check your policy's small print to find out if you're protected and phone your insurer to double check your position. The last thing you want is to be paying out for extra costs like hotel rooms if you don't know for certain that you'll have the money refunded by your insurer.
The Association of British Insurers said: "It is an urban myth that insurers are relying on an 'Act of God' clause to get out of providing cover for this event. Where this event is not specifically covered by your insurer, some are offering ex-gratia payments for customers stranded abroad."
However, many are not so it's vital to get in touch as soon as you can to discover exactly what your position is.
Bob said: "Our position is clear - this is exactly the type of event that customers buy insurance for and they should be able to claim for the cost of their lost holidays and costs that they occur. Insurers must not use their small print to try and wriggle out of this one."
If you've purchased cover for a single week and are now stuck overseas for longer, you may well be worried that you're uninsured - so if you were to have an accident, for example, would your original cover pick up the bill? The good news is that it will. The ABI has reassured travellers that all single-trip policies will automatically be extended for stranded customers, typically for up to one month.
I'm booked on a package holiday, what are my rights?
There's good news if you've booked a package holiday. These types of trip have their own protection in place, meaning the operator will refund you for your entire trip if it's cancelled.
However, you will probably also be offered the chance to defer your trip or move onto a different holiday of a similar value.
What if I'm running out of money?
After the expense of a holiday, many British people will be struggling to afford the additional costs that being stranded overseas is causing them, but the British Bankers Association says that banks understand that some people are being hit with unexpected costs and are trying to support requests for extra finance.
Phone your bank or building society as soon as you can if you're concerned about going overdrawn without permission.
Advice for travellers stuck overseas
The Foreign & Commonwealth Office (FCO) is offering online and telephone advice to those stranded overseas and their friends and family back in the UK.
You can access that information through its website or by calling the following numbers:
For passengers overseas - +44 20 7008 0000 or contact your local British Embassy or Consulate
For those in the UK - 020 7008 0000.