I think you can have 3 lights as you show in your pic if I am reading this correctly:
REQUIREMENTS RELATING TO OPTIONAL MAIN-BEAM HEADLAMPS
Any number may be fitted and the only requirements prescribed by these Regulations in respect of any which are fitted are those specified in paragraphs 7, 10 and 12(a) of Part I and, in the case of a motor vehicle first used on or after 1st April 1991, paragraph 5 of Part I.
Source:
http://www.opsi.gov.uk/SI/si1989/Uksi_1 ... _en_10.htm
I saw that dipped beam headlamps (or optional dipped beam headlamps) can pnly be fitted in pairs and think I read that you can only have 2 anyway (1 on a motorbike and 3 wheeler)
Steve