AFTER increasingly dire warnings about various corners of the world, it is pleasing to report that, according to the Foreign Office: 'There is no reason not to visit Ethiopia.' Having said that, the FO travel advice unit says the Sudan and Somali border areas should be avoided. There are, says the unit, plenty of reasons not to visit southern Sudan, where a civil war has been fought since 1983. Call 071-270 4129, or consult BBC2 Ceefax pages 564 onwards for up-to-the-minute advice.