From Dr Jill Crista today, I thought this was interesting:
For people affected by mold, I use D in the liposomal form, because mycotoxins impair absorption of fat-soluble vitamins like D. Liposomal forms work around this impairment, and because they maximize absorption, less dose is needed overall for the same impact.
I also like supplements like Liposomal D+K which include Vitamin K. Studies show that supplementing Vitamin D when someone has inadequate levels of vitamin K can increase the risk of calcium deposition in arteries and soft tissue. D+K prevents this risk.
I use varying doses, depending on the level a person is starting from, and shoot for lab values of 60-90 ng/ml or 150-225 nmol/L.
For UK, you could use this supplement. Or this one. I go for 160-220nmol myself. See my Vit D factsheet here. Remember that every 1000iu will generally increase Vit D levels by about 7-10nmol. I always find that titbit useful!