From the town of Windermere itself take the A592 North over Kirkstone pass and alongside Ullswater.
Aira Force is a decent stop off alongside Ullswater, about a 1/2 mile trek from the car park but well worth the walk, the cafe there is owned by a polish couple and has some decent food!
End of the A592 at the roundabout there's a place called the Rheged center, nice place for a coffee.
Go east at the roundabout for 2 roundabouts till you reach the A686 (Hartside pass) at the top of the climb there's a bikers cafe, nice stop off for a few pics if the weather is fine.
Just before Alston take the A689 north to Brampton, if you miss this road you can always continue to Haydon Bridge and turn onto the A69 west there.
At this point you can continue into Carlisle for a mooch around or as a short cut back or...
Take the A6071 at Brampton north/east to Longtown and through onto Gretna, visitor centre there has a Starbucks.
From here take the M6 south till you hit junction 44, there is a new bypass opened up that will take you around Carlisle as apposed to through it and is much recommended!
Once you hit the roundabout with the turnoff onto the A595 continue straight over down "Peter Lane" till you get to the B5299 follow this road west through Dalston onto Caldbeck, there are a few nice places in Caldbeck for a coffee or coke and if you can find the "watermill cafe" it has some nice food!
Continue on the B5299 to Mealsgate, turn west and take the A69 to Bothel, here turn south on the A591.
At the roundabout near Keswick take the A66 west till you get to Braithwaite and the B5292, take the B5292 over Whinlatter pass, the visitor center here is a nice spot for coffee, however Luchini's ice cream van in the lay by just at the top of the first big climb is a nice spot for a few photo's overlooking the valley.
Continue west on the B5292 till you hit the B5289 heading south, take this road past Buttermere and over Honister pass there's a slate mine at the top of this pass which is a decent stop off. All the way past Derwentwater to the end at Keswick.
Turn right, through Keswick on the A5271 east till you hit the A591 south, this road will take you past Thirlmere, Grasmere, Rydal water and back to Windermere itself. Grasmere town is worth a nosy round, very touristy but quite a few cafe's.
A long run but on a decent day with the sun out you'll never want it to stop!