In the UK, there are neither resident nor wintering Bluethroats; they are passage migrants only and number between 85 – 600 visiting pairs in total. The best time to observe them is is during their passage, which occurs between May and early-June, and again between August and October.
On passage they visit only coastal areas of the UK, appearing in Lothian in Scotland, all the way down to Kent and west towards the tip of Cornwall. They have a preference for areas of thick vegetation, as well as patches of open ground. In fact, should you view one on open ground, you might notice it hopping across the ground and flitting in and out among bushes; a famously shy behaviour.