Here is a site explaining the UK Air Passenger Duty which they are at pains to point out is not a tax but an excise duty (interesting tautology here, I guess it means that Tony can stand up for lower taxes somehow). The amount is £5 to the EU and Swiss airports where the passenger can exit into France (eg Geneva). Its only charged on outward flights.

The PSC is a passenger service charge levied by the airport (Ticket code UB) all the rates are here. For Stansted where Ryanair flies from its £4.40 for departing flights. Gatwick its £6.80, Luton it's £8.00 (Stelios was right!). Appears, for these airports, to be only charged on outward flights.

The airline insurance levy was introduced after 911. It varies between airlines. According to Ryanair they say here that they will charge $3 per passenger trip. That is about £2 per person per way. This is an amount set by the airline NOT by an insurance company. eg for Ryanairs latest figures of 19,232,788 passengers it means the insurance levy has raised about £40m. Interestingly the annual report fails to break out the cost of insurance. My guess it comes under "other costs" total in 2003 annual report was 59m Euro about £39m this includes all admin costs as well. surprisingly for such an emotive issue the amount is not shown as an amount.

Now need to find charges levied by French.

Ryanair now offering to pay you £1 each way when flying with them. sounds a bit dodgy to me.

When I booked St Etienne flight on 14th Nov. 2003 I paid £0.96 for the flights. UK air duty was shown at £10 and airport tax was £10 making a total of £40.96 for two people return.

For the same flight booking today. Total cost is now £55.12 with flights reduced to £0.20. Taxes on way out now; £12.80 for PSC - Non refundable, £3.72 insurance levy, £8.00 UK air duty; on way back a government tax of £17.22 an airport tax of £9.62 and a consistent insurance levy of 3.72.
Making total taxes, fees and charges at £55.08, flights at £0.40.

Interestingly the site shows flights at £0.01 but actually charges £0.10!

Neer mind I suppose its still very cheap - but it would be better if they were a bit more straightforward.