There are two different matters here. Taking your databases and intellectual property and also “stealing” the intellectual property in your idea.
There is no intellectual property in an idea. So, if you come up with a fantastic business model that is nothing to stop someone else copying it.
For example, you come up with a business website which compares insurance premiums from all the insurers. You cannot copyright or otherwise protect. It was possible, there would not be the number of price comparison sites that there are.
If however he has actually taken physical data and is using that, it is theft becomes a police matter. A financial adviser was recently ordered to pay £10,000 compensation and get a criminal record for taking a client database from his previous employer. It is not the names and addresses which is the intellectual property the actual list that contains them.
So, you can only apply for an injunction if he has taken that data which also is a police matter. If he has just taken the idea, then it’s a complaint to his Regulator.
If you’re applying for an injunction you do it under Civil Procedure Rules Part 8 but be aware that if your injunction fails the court does not consider that you have a course of action, you could end up with a substantial legal costs order against you.