I'm leaving for my first trip to England and I'm using London for a base for 10 days and want to travel to different areas such as Bath, York, Cornwall, Portsmouth, and such during those days as day trips. Can anyone tell me, will I be able to do this easily by train, bus?
Yes- you can do all of that by train or bus! I love to base in London and do day trips. Here is a link to an article I wrote about doing just that last year. It was in AAA Carolina's "Go!" magazine. If you want flexibility about dates and times rather than having to commit to exact day/time, get a BritRail pass. Feel free to private message me- we have been to the UK more than 40 times. (by the way, Cardiff Wales also makes a great day trip- as do Canturbury, Dover, Windsor, etc......) If this link asks for a zipcode use 28208...
http://www.aaacarolinas.com/Magazine/2008/Jan-Feb/britain.htm
Bath, York and Portsmouth can be done as day trips by train from London. Buses will take longer. For reasonable fares book early otherwise it will be expensive. Use this site to check times and fares, for both trains and buses, and book tickets.
http://www.nationalexpress.com/home.aspx
IMO Cornwall, which is a county rather that a town/city, is too far for a day trip and getting to places there is not so straightforward when using public transport.
Would you believe there's been a book written about it:
Frommer's Best Day trips from London
or
just google "Day Trips from London" and you'll get lots of information.