You probably mailed the commercial office of the UCL renting out assets.

It would be worth a try contacting people from the department of computational-biology

And asking if they know of someone inside the university potentially interested to patronage/sponsor the event with a cheaper venue.

Mentioning that the LPW is non profit and that participation is free.

Plus probably a link to "How Perl saved the human genome project" and mentioning that the UCL is using BioPerl. Of course there are more universities in London.

I would do it, but I don't feel comfortable with British in between the line codes of politeness.

For comparison, the local branch of the Chaos Computer Club is running a huge 4 day workshop in my old university for free.