You’re best off going to a shop like Wholefoods or Planet Organic. All their stuff will be pretty good quality. I like Viridian, Wild Nutrition and Together. The latter two are food grown which sounds better than something made artificially. I also highly recommend Spatone for iron. It’s sachets of iron rich water - either get the plain one and mix with fresh orange juice (vitamin C helps iron absorption) or the one that’s mixed with apple juice which you can drink neat. You can buy it in supermarkets and some chemists also stock it. You have to be careful with iron as it can mess up your digestion but Spatone doesn’t. Don’t forget to add in Vitamin D too - everyone should be taking it in the winter.