Coolant loss

Apologies everyone if this has been covered before, New to this forum,

My wife has  2003 KA collection, had about 2 years now and to be fair it ain't put a foot wrong in that time, that was until last Sunday, she took it out for a 30 minute drive and about 5 mins from home she says the engine temp warning light came on and the engine ( 1.3 duratec) started to rattle, so as we live at the bottom of a hill ,she free wheeled it home ( engine on tick over for steering & brakes)

I popped the bonnet and the lump was well warm, fan running like a good un and the header tank was doing a great impression of a boiling kettle.

So car was parked up to cool down and wasn't moved until I took it to work today, before setting off I checked the coolant level in the header tank ,there was still some in but not a lot,so topped it up and set off, 10 minute drive to work, engine hardly got warm, parked her up all appeared normal then after about 3 hours I noticed the car was leaking coolant, managed to get underneath and found the thermostat housing was leaking, ordered one for same day delivery.

New housing had arrived by the time I got home so set about getting the swop done, all finished, topped coolant up, no leaks...whooppee......Not so quick, started engine up, left it to tick over for 5 minutes, stat housing still dry but coolant leaking freely from other end of the engine bay ( o/s), so now I'm thinking duff water pump and or seal ( best case scenario) or cracked block (worst case),

Really sorry it's been a long one but here is my problem / question, the coolant leaking now is cool to the touch but the water in the pipe work and header tank is hot, surely if the water was leaking from the engine via the cooling system, it would be hot too ...wouldn't it ?, so if not the cooling system where else could it be coming from ?

Again apologies for the length of post but I need to get to the bottom of this asap ,wifey works shifts and I figured the more info the better,

Thanks in advance guys