Obligated to have UK license if you have a european one?

I actually drive with my license from Spain- am I obligated to get a fully Uk license ? or can I drive with my EU license? if so.. do I have to re-pass any exams driver´s test etc?? I´m not sure I think european don´t have to since we´ve already got issued our lisence in the EU. But not sure..any hints?
thanks UYK family

http://www.dvla.gov.uk/drivers/drvingb.htm#2

this is the link that explains what to do if you're driving on a licence issued by another EU member state.  basically if you have a licence from Spain- you can drive on that for as long as that licence remains valid. 

oh great link! :)thank you so much meggles!

Yep, that came in a few years ago.  You can swap a license from any other EU country for a UK license with no tests, but can drive on that foreign license for as long as it remains valid if you wish.

Then the fun starts with the way rules contradict themselves.   

For example, Brits expatriating to Spain or France are told that under the new rules they can drive on their UK license for its period of validity.  But DVLA still insists that a UK license must, by law, have their current address on it.   And guess what?  They won't accept a non-UK address.