Although Billund is the "Mecca" for the Lego enthusiast I can heartily recommend Legoland in Germany.
We stayed in the Lego village cabins and they were great. They have built a Knights Castle Hotel for this year.
Food is really reasonable and in the evening after the park closes they have things to do in the accommodation based around the village - there is a lake, bowling alley, buffet restaurant etc. The atmostphere there was lovely.
The food is really reasonable as German people really won't pay silly prices for snacks and drinks. The park itself is better than the UK and on a par with Denmark.
You could drive over on the ferry/Eurostar and see a bit of Bavaria too.
Denmark is eyewatering in terms of cost of living.
We went to billund last year. Throughly enjoyed ourselves children were 11 & 9 at the time. We've never been to the UK one so can't compare unfortunately. We did go August 13/14 and the Danish children had gone back to school, so wasn't as busy. The swedish children went back to school the following week so it would have been even quieter. We stayed at the legoland hotel, quite expensive - room was small for the 4 of us but the food was good and because we were guests at the hotel we were allowed into legoland the evening before our tickets were valid - if that makes sense - so we an hour to familiarise ourselves with the place. You also got free entry into the local swimming pool which was next to the hotel.
Have any of you been to the original lego land? How do you rate it please? We are considering going this summer. We haven't been to the uk one as its a long way from us but thought if we were going to make the effort then maybe we would go to Denmark for the original, is it better/different? Any thoughts much appreciated.