The transport facilities in the UK are very good and can be very reasonably price particularly if booked in advance. National Express runs coaches up and down the country every day of the year.
They also run services to all of the major Airports (www.nationalexpress.com).
You may prefer to take the train. For timetables and destinations please visit www.nationalexpress.com.
For tube enquiries and maps please log on to www.tfl.gov.uk.
Make sure that you get your student card once you have arrived as you can receive great discounts on travel. For very cheap coach and train travel log on to uk.megabus.com.
(In order to get a student card you will need to bring a passport sized photograph with you)