car - 2006 ford focus sport 1.8 TDCI.
Has had about £2,000 on repairs in under 2 years.

over a year ago began loosing water and chemical test indicated bad head gasket, however 15 months on it still runs great, no smoke, no power loss, no oil/water mixing, just having to top up water time-time. I'd have it replaced proper but this car is suspected to have other big problems so I'm unsure what to do.
I bought some steal seal, I want to use it within next few days. My car currently just has tap water so I need to drain the water and am going to refill with antifreeze, I bought antifreeze today, it is Anti-Freeze + coolant in 1. I am not sure if it contains water ?

On the steal seal it claims not to be compatible with waterless antifreeze. if this antifreeze is waterless would it be okay to just add tap water to ti ?

cheers