I looked and found there was one, about 7 years ago

Only 351 supporters!

http://www.thepetitionsite.com/1/real-ale-for-all/

Still, I gather that Guiness have been looking for alternatives to isinglass.

I'm sure no-one is killing fish just for their swim bladders - must be a bi-product just like so many other product constituents.  Seems to me that while most people are eating animal products there's no point in wasting the bi-products of the resource.  There are alternatives for those that want to avoid touching anything containing animal products, if they look into it.  They may have to pay more, but that's their choice.

£5 notes are a bit trickier - they will have to demand change in coins, or wear gloves!  I don't think fivers ever come out of ATMs and I suppose that after this petition the Bank of England wont be putting tallow in new notes of other denominations when they are produced, and probably not in fivers in the future.  What then - will vegans and certain religious groups check the serial numbers of fivers before accepting them?