I would go straight to Llangollen basin the first night as there are lots of pontoons. If by some fluke all the pontoons are full just head back down and take the first available mooring.
There is water and electricity on the pontoons and also the towpath moorings have rings, water and electricity.
The charge was £6 per night but you can only stay for 2 nights.
Don't worry about the narrow bits but make sure that you send someone in front to check if the way is clear - use walkie talkies or mobile phones to communicate.
All the locks, tunnels and aqueducts are busy at peak times but if you sail early or late you may miss the queues.