From Sheffield railway station, it is best to catch the tram. Do not go to the main entrance/exit of the railway station, but instead follow the signs to the tram. Catch any tram from the near platform (do not cross the lines). The fare is one pound and tenpence. If the tram has destination `Cathedral' then it terminates in the centre of the city; when you get there, cross the lines and catch the next tram in the same direction (your ticket is still valid; do not buy a new one). All other trams go to the University (and beyond). The University stop is clearly marked. Go to the near side and walk uphill along Leavygreave Road towards the seven-story building; this is the Hicks building. There will be signs directing you to the lecture theatre.
Other regional airports are described on the University travel page. It is generally better to avoid the London airports if possible. I am told that Birmingham airport is a viable option if you cannot get a direct flight to Manchester.
There are at present no plans to provide transport back to Sheffield on Wednesday evening. If you plan to attend the dinner but not the Workshop, please let Kirill Mackenzie know as soon as possible.
If you need to go direct to the workshop without attending the Wednesday afternoon lectures, please let Kirill Mackenzie know as soon as possible. Some advice is here.