Wow - some ballsy suggestions for 4 year olds! V impressive (?) if your daughter could manage Fairfield Horseshoe and Jacks Rack. IMO - more that a tad optimistic and I have been guilty in the past of taking my kids on scary things!! Water is likely to be v cold for a 4 year old, the memorial at Loughrigg Tarn would testify to that.* Sorry to be a killjoy.
Hours of fun can be had on Loughrigg - try finding hidden ways down to the Caves from the summit.
Hodge Close Quarry and Cathedral Quarry linked in with Tilberthwaite - lunch at Three Shires?
Tom Heights/Tarn Hows from the Coniston road (to avoid the grockles)
Steamer up Ullswater to Howtown and then walk back - still a long one for a 4 year old.
* boat out to the island on Grasmere (the lake is surprisingly shallow between Island and the road, so could be warmer to swim in. Alternative "safer" semi-wild swim is to take road to Hawkshead. Turn L about 1 mile out of Ambleside and over bridge past Brathay Hall. There is large pool (The Dub) with easy parking right there. 5 mins from Ambleside.