[206dael]

Any Excess smoke from the exhaust?

If it's not leaking from any joints or pipes, the only other place it can go is into the engine-in which case, faulty head gasket.

Check the colour of your oil. Is your oil filler cap covered in a creamy gunk?
Also, when your open the expansion bottle, is there lots of gas escaping?

All signs of a blown headgasket.

 

[206dael]

Does sound suspicious with the engine struggling to start.

I'd definitely consider a bad head gasket.

Double check all your pipes and joints for leaks. (having anti freeze or a coloured coolant in the water makes this a lot easier)

If not, I'd probably go straight for the head gasket.