there are so many events for my child(ren) to attend...
In summer there are so many activities and events for my children to attend that I can't find time to make other plans.
「こども関連の行事が多くて」＝ there are so many child-related events... / there are so many events for my child(ren) to attend...
「夏はこどもの習い事や学校のイベントが多くて忙しいのでスケジュールがいっぱいで、なかなか予定が空かない」＝ In summer there are so many activities and events for my children to attend that I can't find time to make other plans.
ボキャブラリー
child-related events ＝ こども関連の行事
attend ＝ 参加する、行く
activities, lessons ＝ 習い事
can't find time ＝ 時間がない、スケジュールが空かない
make other plans ＝ 他の予定を立てる
イギリス 
