Ekia,
Try the search function here on pprune - there's loads of stuff, particularly on how Heathrow manage their situation at the moment.
You might also try searching under International Civil Aviation Organisation (ICAO) ICAO is a body operating under the auspices of the United Nations and set international regulations that every country (including the United States) has signed up to abide by. The UK has an excellent track record in this regard, but other States only pay lip service in many aspects. Use of parallel runways is one such.
Heathrow are currently exploring the possibility of using their 2 main runways as independent runways in order to increase capacity and improve flexibility, even though technically they're not quite far enough apart. Many US airports operate simultaneous approaches with much less spacing than Heathrow. I would imagine risk assessments will show no particular problems at LHR.
Cheers,
The Odd One