Microsoft has consolidated the registration process for all their Cloud services for Not for Profits into a single page:
https://nonprofit.microsoft.com/#/register

These are the plans available for qualifying Not-for-Profit Organisations in the UK:
https://products.office.com/en-gb/nonprofit/office-365-nonprofit-plans-and-pricing

You may also qualify for a credits to use the Microsoft Azure platform to the tune of $5,000 annually:
https://www.microsoft.com/en-us/philanthropies/product-donations/products/azure

If you need any assistance in making the most of your Microsoft donations, please get in touch, and we will help you.