Hi. I had to do this the other day, when the Argentinian embassy had my UK passport while my performance visa was being attached to it. Border control at AMS were wary of me, a Brit, travelling on a Chilean passport from the UK to NL, but let me in and out no problem. Then I returned from AMS into LCY on my Chilean passport. The Border Force agent at LCY was not happy about it. She wouldn't endorse my entry into the UK as a Chilean, because she didn't believe that my behaviour in the UK would be that of a Chilean tourist (i.e. I might work, or buy property, or marry, or have kids or something). So, after grumbling, she used my Chilean ID to identify me as a UK citizen and let me in. So it's not always plain sailing.