It's true that leadwork is no longer on the course. I started my apprenticeship in 2006 and was one of the last cohorts to do sheet metal work including lead. Now I work at that same trade school as workshop technician. Fortunately we kept all the gear so if any employer wants their apprentice to learn lead welding and dressing, we find the time and teach as much as we can. We just call it an "Extension activity" and we teach them as much as we can over a few weeks or months, slotting in lessons where we can. It's better than nothing and whilst there is no qualification for it now, some of the employers are pleased we've kept it going. Most aren't interested sadly.
I have "Sheet metal fabrication" on my indentures which no longer appears on their final qualifications paperwork but at least they get the chance to learn if the employer wishes. I would hope that other colleges do the same to keep it alive within the trade.