Based on this information your realistic target time is ~30:30 +/- 15s.
I'd say do two workouts a week, one as something race-specific for the 10k/5k and one as some sort of tempo combo with a large dose of pretty chill threshold work plus a small dose of some mile effort work at the end. If hammering out a bunch of 400s at mid-60s pace is what it takes to give you confidence it's not the worst thing to do, but it's not the best thing to do IMO unless you have already done some intermediate workouts that bridge the gap to that type of session -it's a big shock and isn't all that specific to 10k demands. We think of the 10k as a track event so we often want to hammer out a lot of fast-track work in preparation, but at a certain point that speed and anaerobic capacity doesn't really do much for us because if we go too deep into anaerobic territory too early in the 10k race we're gonna be toast anyways.
Mostly I'd say just refine your current fitness with workouts of a similar structure to what you've already been doing but slightly more specific to the 10k -get somewhat familiar and comfortable at 10k pace.
Some race-specific workout examples, similar to the 3min or 5min fartleks you've already been doing but a little faster and with more rest:
8-10x1000m @ 10k pace /1:30-2:00 rest
5x1600m @ 10k pace /2:30-3:00 rest, 1x1000m @ 5k pace
4x(1000m @ 10k pace/2:00 rest, 1000m @ 5km pace/3:00min)
Some tempo workout examples:
25x400m @ 10k pace /30s rest
6x5min threshold /60-75s rest, 5min rest, 5x200 @ mile pace /easy jog back recovery
10x3min threshold /45-60s rest, 5min rest, 5x200 @ mile /easy jog back
All pretty boring simple stuff but that's the whole point.
The day before each workout is a good place to slot in some earnest strides (8-10x 100m) which will help with the neuromuscular aspect of speed. Ideally would do this after a short afternoon double with some drills so that you are properly warmed up and can comfortably get down to faster-than-mile effort.
Not sure how comfortable you are at 90mpw, but I'd say keep overall volume high the next two weeks, cut back to whatever a comfortable "baseline" volume is the week ahead of race week (maybe ~70mpw?), and then just do whatever will have you feeling fresh on race week.
You may not get 4:40-4:50 mile pace to feel particularly comfortable in ~1 month, that's probably a job for another training cycle and mostly aerobic work.