The UK Border Agency (UKBA) has said the following about travellers whose visas have expired and who have been unable to travel due to volcanic ash ending up in the atmosphere after the eruption beneath the Eyjafjallajoekull glacier in south-western Iceland; "…We appreciate that this is due to exceptional circumstances beyond your control…" UKBA has also said that if your UK visa has already expired you should keep documentation confirming your travel plans showing that if the eruption had not occurred you would have left the UK in time and not become an overstayer.
The volcanic eruptions have resulted in most flights throughout Europe being cancelled since last Thursday. Eurocontrol that is responsible for co-ordinating air traffic control in 38 Countries, said that on Saturday 17,000 out of a total number of flights expected on a normal day of 22,000 were cancelled in Europe. It is uncertain how long flight disruption in Europe will continue for. It is possible that a partial ban on flights will continue until late in the week. Some people have speculated that disruption to flights will continue for much longer. The flight ban is costing airlines an estimated US$200 million a day. If the flight ban is not lifted soon businesses that rely on migrant labour may also start to suffer.
If you intend to travel soon to an European Country for work or pleasure you should make sure before making travel arrangements about flight availability and if the relevant European Airport is actually open.