Hi Neil,
Has the cambelt been changed recently or any other service work.
- Check the oil, is there any white gunk on the dip stick or the filler cap or any oil in coolant header tank.
- Fill the system with coolant, let it sit for a couple of hours then start following the coolant pipes inspecting all the joints for signs of moisture.
- Take the bottom engine cover off and with the engine running check for any leaks with a torch.