There are a handful of more generic crowd-funding platforms out there, so no need to build your own. A good candidate website would be more than enough to build.

As a bonus, crowd-funding your candidacy would give you early validation. And, as a comment below says, you should be able to convince enough people to scrape together £10k, if you expect to run. Fail fast, and all that.

You certainly have my donation, and my vote if I can still afford to live in London by election-time!

[1]: https://news.ycombinator.com/item?id=9100275

> Maybe I will give it a shot. At the very least it force the candidates to address rent control as an issue.

I doubt it will force anyone to do anything, least of all the candidates.