I'm afraid it will be very difficult to choose subjects such that you will be eligible for both MD and MEng (Electrical).
To qualify for entry into the MEng (Electrical) 2 year stream, you will need to have completed an Electrical Systems major in your BSc. To qualify for the 3 year stream, you will need to have completed 25 points (two subjects) of first year mathematics and 25 points of first year physics.
For entry into the MD, the prerequisite subjects are - as mentioned - "Biochemistry & Molecular Biology", "Human Physiology" and "Principles of Human Structure". These are all second year subjects, but they themselves require prerequisites. To do all these subjects you will need to have completed 25 points of first year chemistry and 25 points of first year biology.
Thus, to keep your options open to the end of first year between the MD and the MEng (Electrical) 3 year stream, you will need to sacrifice your breadths and complete the following;
Chemistry 1 | Biology of Cells and Organisms | Physics 1 (any) | Calculus 1 or 2
Chemistry 2 | Genetics and the Evolution of Life | Physics 2 (any)* | Calculus 2 or Linear Algebra
* Might not be able to do Physics 2: Life Sciences and Envrionment; you'd have to check this.
If you wanted to do the 2 year stream of the MEng (Electrical), then - as said - you'd need to complete an Electrical Systems major. In this case, you would replace the Physics 1 and Physics 2 with ESD 1 and 2, respectively. However, I am unsure whether there are second year subjects in the Electrical Systems major which require first year Physics subjects as prereqs; if this is so, then this path would be practically impossible.