If you like petitions:
End tax dodging by multinational corporations in poorer countries
Churches Action For Tax Justice
https://www.catj.org.uk/pertition.html
No toxic trade deal with Trump
Global Justice Now
https://act.globaljustice.org.uk/no-toxic-trade-deal-trump?
Make sure big companies pay their share of corporation tax
38 degrees
with special reference to creative industry tax relief
https://speakout.38degrees.org.uk/campaigns/gta-vs-nhs?utm_source=facebook&utm_medium=advert&utm_campaign=27_1_2020_rockstart_north_lal
Make the wealthy pay their fair share
Tax Justice UK
if you are in favour of a wealth tax
https://you.38degrees.org.uk/petitions/make-the-wealthy-pay-their-fair-share