You can take a bus from Patterdale to Grasmere via Keswick, Bus Station (K) (Booths Supermarket) in around 1 h 23 min.
How to get from Patterdale to Grasmere
From Patterdale, Hall (Patterdale Hall at Grisedale Bridge) line 208 bus to Keswick, Bus Station (K) (Booths Supermarket) then line 555 bus to Grasmere, Heaton Cooper Studio (Village Centre). 1 h 23 min £8. From Patterdale taxi to Grasmere. 16 min £42. From Patterdale drive to Grasmere. 16 min £2.