It would appear that the best guidelines for detection of Malaria to follow in the UK would be the one from the British Society for Haematology. The direct link for this guideline is here. The full section on Malaria can be found here.
Direct link for Guideline
http://onlinelibrary.wiley.com/enhanced/doi/10.1111/bjh.12572
Direct link for Malaria section on BSH website
https://b-s-h.org.uk/guidelines/guidelines/laboratory-diagnosis-of-malaria/