Recommendation for system cleaner and inhibitor

[thepurpleblob]

Had my central heating in bits and found everything to be full of the black gunge!

Now it's going back together can someone recommend a good treatment to clean it out and then a good inhibitor (or what's the best thing to do with it)? I've had a good look around and I'm a bit overwhelmed with the number of products and packagings. How much to get for a large-ish three bedroom house (two rads in every main room).

Any advice much appreciated. Cheers.