Bad Luck indeed. The bulb will set you back between ukp 65 and ukp75 depending on shop. I have seen them in Roho watersports and Divers Warehouse, but would recommend you phone around a few shops and compare costs. Most will have to order them in anyway.
In case you are interested the bulbs are manufactured by WelchAllyn in the States and are a 10W HID solarc lamp with SEL connectors part no M10N001
Available on the net here for usd 120:
http://www.walamp.com/lpd/webstore/d...ber=M10N001-1#
But you might get charged VAT and import tax on arrival in the UK (17.5 and 6%)
Best
Anke.