UK: Computer controlled wood milling machine advice required

I have to construct a few hundred hollow hardwood boxes. These are to be open on the underside with some detailed but shallow carving on the 4 vertical sides and a couple of 3mm drill holes in the top and one of the sides. I need tolerance for the holes of +/- 0.2mm. The box dimensions will be 10x10x5cm (w,d,h)
I am looking for a service in the UK that has a computer controlled machine to mill such an item from a solid hardwood block.
Does this seem like a sensible approach to make the item? Can anybody recommend a UK service that can carry out this task?
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