No, it won't really be useful. It combines UVA and UVB and only has milliwatt accuracy and not microwatt (1 milliwatt = 1000 microwatts). You need to know how much UVB since this is what is used to synthesize vitamin D3, and it should usually be around 35-100 microwatts, not milliwatts. Even 1 milliwatt would be way too high.
Solarmeter 6.2 is the best option because it only measures UVB and has microwatt resolution.