As far as I know, Gamstop mainly deals with self-exclusion from UK-licensed online gambling sites. Since National Lottery draws do not fall under the category of online gambling, it is unlikely that Gamstop extends to them. I'm well aware that it might seem to an inexperienced player that https://sitesnotongamstop.net/how-long-does-gamstop-last/
understanding Gamstop and National Lottery might have something to do with it, but that is absolutely not the case. Nevertheless, it would be great to hear from someone who has more detailed knowledge or personal experience with Gamstop and the National Lottery.