Here are a couple of ideas.
Use this link to find your nearest Home Improvement Agency
http://www.findmyhia.org.uk/ They can often advise on local grants and schemes.
If that doesn't work out try using the grants search tool on the Scope website to see if you can identify a suitable charitable grant giver that you can apply to:
Jean Merrilees BSc MRCOT
You can read more of my posts at: https://community.scope.org.uk/categories/ask-an-occupational-therapist