Mosquito + other bug repellents work pretty well.
In the Midlands - and in most other area of England (Wales , Scotland + N Ireland are different) - it depends where you are + time of day. If you are near water or marshy ground there will be more flying biting critters, particularly late afternoon onwards. Horse flies can be a problem in open country any time of the day. I seem to be irrisistable to most of the flying biting insects, so use a hat, cover up + apply bug creams/sprays depending location + time.
Boggy ground anywhere can be an issue - have had bad experiences in the Lake District as well as here in Derbyshire, but there is nowhere like Scotland