For the first few days, you will literally have no idea what anyone is saying to you. If they're speaking in Gaelic then obviously you'll not be able to understand them, but even when they're speaking English you'll have to get them to slow down or get their friend to translate for you. If you're not used to it, the Scottish accent can be difficult to understand so you might have to practise your smile and nod whilst being completely unaware of what you're smiling and nodding at. Remember, you can only ask them to repeat something three times because anything after that is rude.
