I learned to heel and toe over 20 yrs ago but never did or could use my heel - my size 12A feet are way too long to stick my heel over.
I've always just used the right side of the brake pedal and rolled my ankle over to press hit the gas with the right edge of my foot. I use running shoes too which add width to my narrow feet. I would suggest learning on the street with those type of shoes before progressing to the true driving shoes.
I haven't found any problems with the pedal placement of either my 1M or my previous e90 but have added a thin gas pedal cover to a VW that had the gas pedal too far away. Not to bring the gas pedal to the same level as the brake pedal but to give it extra width.
If you're going to buy pedal covers I would suggest that you get one with a smooth gas pedal cover and textured middle one. The Turner set looks nice!
Hope this helps.