Where is the nearest Airport to Saalfeld where I can travel to UK?
Ryanair have flights from Altenburg to London Stansted. Altenburg is about 90 km from Saalfeld.
British Airways have flight from Dresden to Gatwick. Air Berlin and Germanwings have flights from Dresden to London Stansted. Dresden is about 175 km from Salfeld.
I think your best bet is ryanair from Leipzig Altenburg to Edinburgh, I think they do 3 flights weekly, once in edinburgh you also have glasgow close by - consider flybe, ryanair, bmibaby and easyjet as low cost airlines in UK and most of the time its cheaper than the train to get around especially if any of them have any deals on.