An organisation has been set up called iBuy2Give, which allows charities to register their Good Causes, then members of the public can donate to those causes while purchasing items in a way that is similar to Groupon.
The scheme is registered with the Fundraising Regulator, and you can read more about the organisation here in an article in UK Fundraising.
You can register your charity or good cause (including schools, clubs, etc) on the iBuy2Give website, and encourage your supporters to make purchases through them.
Given the current situation around the Corona virus, please check with individual organisers regarding events listed in these pages, to ensure that they are going ahead, before you travel.
Also, please bear in mind the advice not to attend if you feel unwell, or have a temperature, or have been in contact with anyone with the virus.