About a 3/10. Just use some silicon spray or something to grease the heater hose up before sliding it on. Bottom first, then the top end. A long screwdriver will help with the hose clamps (>30cm long)
As mitch said, not too hard. Do it with a stone cold engine. You will need flexible hands/arms and patience. Do them both while you are at it. Ensure you don't disturb any hoses/wiring back there.
just say awkward not too difficult. Torch, screwdriver, hose lube. You may want to sand off any build-up off the hard-pipes to ensure a good seal with the new hoses.
