Hi Frankie,
I used to canoe on Windermere when I lived up there. Canoeing is free though I did have to pay to launch from the public slipway at ferry nab. There are some places on windermere you can launch for free though. My favourite lake for canoeing on was Ullswater and there is a national trust car park half way down the lake. You can park up and carry your canoe across the road to launch it from a pebble beach.
I just phoned the lake wardens office and if you carry your canoe to the slipway and it has no engine then launching is free from Ferry Nab.
Also found this information for you: Boat launching and storage
Ferry Nab is the main public launching area with a public car park, toilet and shower facilities, public jetties, sailing dinghy storage and tender storage. It's the only public slipway available for power boats and large boats.
Small motor boats (5 horsepower or less) may launch from Waterhead. Sailing dinghies, canoes and rowing boats may be launched from serveral areas on National Trust land, Rayrigg Meadow and Beech Hill.
There are several private and commercial launching points, predominately on the eastern shore. These include sailing and power boat clubs, caravan parks, commercial jetties and marinas and several outdoor pursuit and activity centres.
Regards
Clive :)