The EU Succession Regulation was introduced in 2012 with the intention of standardising succession laws across EU member states (but does not apply to the UK, Ireland and Denmark). It is worth remembering however that cross-border issues of course can arise between England and Scotland.
For people who have assets in states which have adopted the Regulation then the default position is that the succession of those assets will be governed by the law of country in which the deceased was habitually resident at death. The exception to this is where a person chooses to adopt the law of their nationality in their Will or were clearly more closely connected with another country at death in which case the Regulation will be overridden.
For example, in England, the default position is that succession of immoveable assets (e.g. your home) are governed by the law of the country where the asset is located whilst moveable assets (e.g cash) are governed by the law of your domicile.
See more about this in our article here.