Found a document which does say that TRVs, a room thermostat etc. are required. It's not in the Building Regs Part L as is often specified, that just says that a boiler must meet SEDBUK A & B ratings. However, these ratings are only achieved by the boiler, if the items above are included in the central heating system.
http://www.gas-news.co.uk/gpg302.pdf
http://www.gas-news.co.uk/gil059.pdf
http://www.gas-news.co.uk/gpg302.pdf
http://www.gas-news.co.uk/gil059.pdf