Name change nightmare

Trying to find information about changing names after getting married is a nightmare. Most of the information I have found says that there is no legal obligation to change your name; but websites such as the DVLA say I have to inform them of a change of name. So far, I’ve changed my name at the bank, but I want to keep my maiden name at work and use my married name elsewhere, and I can’t work out what constitutes legally changing my name – is it changing my bank details, my passport, my driving licence or none of these things?