If you find any sick or injured wildlife there are various approaches you could take. Some would say let nature take it's course, but if you would like to intervene there are organisations and veterinarians which may be able to help you.
If you find a grounded bat (outside or inside your home) call the Bat Conservation Trust to ask for advice. They will likely put you in touch with a bat carer near you. Tel: 0345 1300 228