Hi @Simon C
Thank you for posting your question in the Microsoft Q&A forum.
I truly understand how this feature might be handy for everyone.
Unfortunately, this feature is not available at the moment.
I did find this feedback that requested the same feature as yours.
Need the ability to schedule recurring events on workdays only · Community
My recommendation is voting for this idea, the more people vote for it, the higher possibility Microsoft will consider and making it a feature in the future.
Thanks for your understanding and contribution to make Outlook more convenient to users.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.