So from this, it looks like our minimum number of players coming in between now and the close of transfer window will be 3 to fill 3, 4 & 8.

Left Back, Centre Back and Striker therefore look the most likely positions to be filled over the next week.

Or maybe LB, CDM & CAM if 4-4-2?

In a traditional 4–4–2 system in the UK, the squad numbers 1–11 would usually have been occupied in this manner:

1 Goalkeeper
2 Right back
3 Left back
4 Central midfielder (more defensive)
5 Centre back
6 Centre back
7 Right winger
8 Central midfielder (more attacking)
9 Centre forward (usually a target player)
10 Striker (usually a fast poacher)
11 Left winger

However, in a more modern 4–2–3–1 system, they will be arranged like this:

1 Goalkeeper
2 Right back
3 Left back
4 Centre back
5 Centre back
6 Central midfielder (more defensive)
7 Right winger
8 Central midfielder (deep-lying playmaker)
9 Striker
10 Attacking midfielder (advanced playmaker/enganche)
11 Left winger
(Courtesy of Wikipedia)