Yep, a lot of time and money. As the Europeans don't think anyone elses licences are up to there standard, you will have to do the theory all over again at an approved school (minimum number of hours study regardless of the fact you know it already), flight test, medical, and this will all cost you a lot of time and MONEY.
You will also find it very hard to get a straight answer out of the UK CAA who will keep refering you to LASORS instead of giving you a direct answer to your question.
Want to convert your type rating? Good luck. From what they tell me you need 500+ hours on type or you have to re-do it.
Welcome to Europe...