LN,
I'm about at the same stage as you, having just finished my workshop build I now want it dust free.
I promised myself I would not get involved in Safety on this forum, as that is my profession and I come here to relax.
However having some competence & experience regarding Local Exaust ventilation here is my plan:
1. Basic extractor (£20 from Screwfix) to run when in the shop to keep it cool & increase dilution rates (air flow) thus lowering dust level - for when its warm outside.
2. Before the Autumn buy the machine in your picture (might go for the one slighty bigger than recommended for my shop size.) This will only run when I want to work in the shop but external ambient air temperature is unfriendly.
3. continue to use my B&Q vac (fitted with fine filter) on sander , table saw, lathe etc.
4. Continue to use dust mask when power sanding even if dust can't be seen..
5. continue to monitor (look at dust in the air!!) and stop work if I see it.
6. continue to vac surfaces (not blow, brush or dust!!) at regular intervals
