In the UK they cannot check your emails. You are covered by the Data protection Act. They can only check the details and people that you give them. They are not M15 with spies checking up on people, they have not the time or resources.
They give u about a 3 page packet to fill out and they wanna know EVERYTHING. Atleast 15 diff people who know you 3 more who know you really well. All of ur jobs for the past 10 years. Everything