Business class PC for Charitable organization

I am on a Board of Directors for a local community centre. We have a Charitable Tax Exemption status (CHY number) so we will be applying to get Office 365 for Nonprofit.

Current PC stock is XP and is old and about to fall over.
We are looking for recommendations of a decent spec desktop PC (need 4 or 5) that will take care of daily office type tasks for the manager and employees of the centre. Would need to be capable of running Office 365 (most likely web versions of Word/Excel etc). Also need to be able to do basic tasks such as photo editing and maybe even video editing etc for web site and marketing of the centre.

Needs to be Win 10 so I was thinking Core i5 and maybe even 8GB RAM with SSD if at all possible. Would like to keep costs down sub 450/500 per machine (that needs to include VAT as we dont get to claim back any VAT charges)

maybe I am over specing it but if anyone has any thoughts and/or recommendations please post details

Thanks