Unlike other countries, like the United States for example, long distance bus and coach travel is not particularly popular in the UK. There is a company that actually operates a very good service between all major cities of the country (National Express), but people will still tell you that they prefer to travel by rail or even air.

London is definitely the best served city for the national coach network and there are regular services from all other large cities. Time wise, this is quite a slow means of transportation but this is certainly compensated for through the fact that costs can work out as being reasonable.
If you are considering the coach to cross a vast proportion of the country, think very long and hard about this and check out the timings for the service and crucially, the number of stops being made along the way. It is not unusual for a journey that normally takes four hours by rail to take double this by coach.
There are also some commonly reported problems with failing to secure a seat on a coach, even though the tickets may have been reserved long in advance. There are some complicated reservations’ policies in place here and it is therefore imperative that you verify these if and when you place a booking. Bus travel is more commonly undertaken in the UK for shorter journeys. This is especially the case for getting around a town or city. All major cities and large towns has an extensive bus network and there are also a number of companies that operate services on a regional level. Bus services will tend to remain within a particular county and this is down to the fact that they are often subsidised through the applicable county council.