If you are in the UK and you find a shop that buys from IKON( a lot of them), then you should be able to get them to get hold of a few items for you.
Advanced Nutrients do a
cal-mag supplement Sensi Cal(grow or bloom) which contains calcium and magnesium and a range of micronutrients. Don't think it lists a foliar application, but 20-25% strength should be safe.
Grotek has Cal-Max, which contains calcium, magnesium, iron and fulvic acids.
Another option is Groteks Vitamaxplus which is basically a B-vit supplement and also conatins a range of minerals including calcium and magnesium and a range of micronutrients.