Services over the Easter period vary across different areas of the country. In general, the usual pattern is:
Good Friday: Sunday service. (In some areas it's a Saturday service).
Saturday: Normal service.
Sunday: Normal service.
Easter Monday: The same service as on Good Friday.
So, it's most likely that a normal Saturday service will apply. It should be easy to check because bus timetables for the whole of the country can be accessed here:
http://www.traveline.org.uk/index.htm
Chris