B-B
I don't think "convert" is the right word to use, you will be given quite a few dispensations but sadly you still have a few hoops to jump through, and they all cost money.
Where to do it depends on where you are, US/UK/elsewhere. There are a few places you can do the written tests, not necessarily in Europe.
Is it worth it? Well, how long is a piece of string? If you intend to work in Europe you will need it. Of course, you must also have the right to work there. If you don't specifically need it to fly in Europe, you might just spend all that time, effort and money for nil return.
I hope this helps.
Tam