Seeking professional instruction when you are ready to start leading is highly recommended in both summer and winter. Even if you are competently leading in summer a few days of coaching when you make the move to winter will ensure that you lay good foundations on which to build an enjoyable and safe climbing career.
Learn to lead courses require 2 people so that the students can work as an independent climbing team, with the instructor being on hand by the leader to offer coaching, advice and reassurance. This doesn’t mean that you both have to want to lead climb, one of you can do all the leading while the other learns to be a competent second. Or if you do both wish to lead then this role can be alternated as we progress up a multi-pitch route.