If you don't want to drive, there's a surprisingly good bus network, with a couple of railway lines skirting the outside. From Oxenholme, a branch line continues to Kendal (a market town on the edge of the Lakes, where I prefer to base myself when I go up there, as I find the whole dusty B&B thing in the area rather tedious) and on to Windermere - another good base. For Low Lorton (between Keswick and Cockermouth) you can also access via Penrith.

Windermere railway station then connects you to the bus network proper (as does Kendal bus station).

This map gives you an idea:

http://providerfiles.thedms.co.uk/ea...055083_1_1.pdf

(although note that the bus services are much more widespread in the tourist season)

and you can use Traveline to plan your journey:

http://www.traveline.info/

There are a number of rover tickets that combine rail, bus and ferry. A good guide to getting around is on the tourist board website:

http://www.golakes.co.uk/travel/by-bus.aspx

Of course, there are also long-distance walking and cycle routes if you feel like being more active!