If you wanted to get an idea of B&B prices, one of the best places to look is Smoothhound:

http://www.s-h-systems.co.uk/shs.html

Here's the Southern and South-eastern England Tourist Board site: http://www.southerntb.co.uk/

You mentioned you are starting in Portsmouth and moving east. How far east will you go? Will you go south?

Frances Toronto, Canada