As it is a UK car, there will be no problem in sourcing bulbs. If you find the dip beam too dim (they are notorious for this) you might like to upgrade to 85w from places such as
Powerbulbs
Others suggest fitting a relay dedicated to the headlights so they get a dedicated feed straight from the battery. Mine had this done in Japan but I don't know where to get such a thing in the UK.
Yet another suggestion can be found on
Zedworld who can strip and clean and line the lamp housing. Some love this and some don't. Your choice.
Although I'm not a techie, it sounds as if you've got a switch problem as well - or perhaps this is the basic problem? Try a local dealer or auto electrical specialist.
Good luck - Gio