Coniston lake shore. Feed the ducks and paddle.(less swans than windemere very shallow shelving but stony so shoes that can get wet are handy)
Good paddling spot by the stream at Chapel Style. Just over the foot bridge. Tea and cake upstairs from the Co-Op.
Boat trips on Windermere, Coniston, Derwent Water or Ulswater
Walk from Skelwith Bridge to Elterwater is easy with a push chair. Posh teas at Chesters in Skelwith Bridge
Walk round Grasmere is good will need some carrying I think
If you are up for carrying then Loughrigg is not a bad family walk
Swimming pools at the langdale time share and just outside Windermere. Both pricey day membership but as its day leisure club membership. But might be worth every penny of it really rains