She stays for the three very hot summer months where her normal Palace gets too stuffy. She doesn't like using magic on air conditioning as she thinks it takes too much energy. She feels it is uch easier just to get away from it all for a bit. In fairness, the Palace is huge. Also she sees it as giving her Lord Chamberlain and Housekeeper a holiday (they do not see it that way, they still have to carry out some of their duties at the holiday estate. Their opposite numbers here do the majority but are very aware they are outranked by these two. They're aware of it too).
The Queen loves walking along her long, sandy beaches. She will swim but is not as keen on it as Hanastrew (who is considered as the Kingdom's nearest thing to an athlete, despite her love of chocolate. The girl burns it all off.).