Thanks for your question - I am Sama nd I am one of the UK tax experts.
Yes as you do not supply zero exempt supplies - so you charge at the standard rate.
Link here for you so you can see what charities can have VAT free (either exempt or zero rated or reduced rated. (Also in case they raise this as an issue)
As you can see graphic design services are NOT in that list!
Let me know if I can provide any further assistance