You were lucky to get away with not destroying your engine when your timing belt tensioner went.
However, that said, the cause of all your woes comes down to just one thing---the loose radiator hose clip. This has caused your engine to overheat and as such has ruined it.
Coolant has been forced out because of this and coolant lying on the road does not have quite the same effect in cooling the engine as coolant circulating in the cooling system.
Make sure you have all your bills and some kind of evidence from your recovery service, go to the garage who failed to fit the hose clip properly, tell them you want a new engine and that you do not expect to receive a bill because it was due to their negligence that you engine has been destroyed. Do not agree to any repairs.
If they won't budge, threaten (and if necessary carry on with) court action.