Is it possible to change crestworth astro lantern bulb holder to GU10?

[Dmac]

I have an MK2 astro lantern that I'm using with a modern mathmos bottle. The bottle flows nicely on my modern lamp but is a bit slow on the crestworth. It currently runs on an SBC B15 40w bulb. Is it possible to convert the lamp so it runs on a GU10 and what parts would I need? I'm fairly clueless when it comes to this stuff, is it something I can do myself or would I need an electrician?