If your holiday is ruined by Swine Flu then gather evidence of your ailment to ensure the saga doesn't also leave you feeling financially sick.

If you have travel insurance, this could be your only hope of compensation. But make sure you grab as much proof as possible to improve your chances of successful redress in case insurers try to wriggle out of claims.

Martin Lewis, MoneySavingExpert.com creator, in the new Swine Flu Travel Rights guide, explains this warning for those affected by the pandemic virus.

He adds: "To claim, you normally need proof from your GP, but most sufferers are being told not to go to GPs, so they lack official diagnosis.

"While the trade body for insurance companies, the Association of British Insurers (ABI), says this should be taken into account, it would be hard to bet against some insurers avoiding claims and making customers jump through hoops to prove they had Swine Flu.

"Therefore, work on the presumption this will happen – if your claim goes through with ease, it's little wasted effort. If not, it could help you claim hundreds or thousands of pounds."

Insurers' promise

Update, 23 July. Following the launch of the National Pandemic Flu Service today, the ABI has said insurers should accept as evidence the ID number you receive by phone or online following Swine Flu self-diagnosis. You'll also need to include the label on the prescribed drugs.

However, while the ABI insists you should be covered even though GPs are unlikely to issue official sick notes, it's still to be seen whether its members will adhere to its directive.

Sadly, if you're not insured, or your cover excludes pandemics or cancellation cover, it's likely you won't receive any money back. Yet if you're travelling on a ticket that allows you to re-book, or if your hotel booking is also flexible, you may be able to re-schedule.

If your holiday is not imminent, get travel insurance as soon as possible (see the Cheap Travel Insurance guide). Policies will only cover you if bought before the onset of symptoms.

Gather evidence

Whether you were denied boarding, have been self-diagnosed or were held in quarantine, get as much proof as you can think of. This can include official documentation on headed paper, chemist receipts or even just notes of the symptoms.

You could even take a photograph of youself at an airport or of the mercury reading to prove you have a temperature.

If your insurance claim is rejected

First complain to your insurer. If it doesn't offer a satisfactory answer within eight weeks or rejects a genuine claim then complain to the free Financial Ombudsman Service. See the full Financial Ombudsman complaining guide.