From reading various topics, I see that a lot of lotty owners aren't familiar with the gardening benefits of Epsom Salts, so here goes. Technically, it's magnesium sulfate, the name you'll find it under at the farm supply shops or wherever you get bulk agric. supplies. For our science lotty owners, it's MgSO(little4).7H(little2)O - the K of NPK.
It's also available at the chemists, where they charge about 10X the price the ag suppliers will. I buy it in 50 lb (22K) bag and it lasts quite a while. Not sure if this size is available in UK though. It isn't actually a salt (not a chloride sulfate), just named after someone and the fact that it looks like salt. In the garden, it makes plants grow bushier, produce more flowers and improves phosphorous and nitrogen uptake by roots. Unlike commercial fertilizer, you can never overuse it. It's especially good for roses, peppers and tomato plants. Only plant that hates Epsoms is SAGE.
Here are the recipes - in imperial. Have to convert to metric yourself. Sorry.
Houseplants: 2 Tbsp Epsom to 1 gallon water, use once a month
Tomatoes: 1 Tbsp epsom per foot of plant height per plant - every 2 wks and scratch into soil or dissolve in some water.
Peppers: ditto
Roses: 1 Tbsp epsom per foot of plant height per plant every 2 weeks AND scratch 1/2 cup epsom into soil at plant base to encourage flowering canes and new basal growth. If moving/transplanting roses, soak roots in 1/2 cup epsom/gallon water to help roots recover. Add 1 Tbsp epsom to planting holes.
Use as a weak epsom solution for a weekly foliar spray on most plants to deter pests.
Shrubs, evergreens & rhodos: 1 Tbsp epsom per 9 square ft (3Msq) over root zone every 2-4 weeks.
The results aren't instant; be patient. And this isn't a fertilizer replacement, merely something that enhances fertilizer absorption and plant growth.
Epsom salts are also fab for the skin as a skin softener in the bath - about 1 - 2 cups depending on the size of your bath (or occupancy). It's also a fab detox as it's absorbed by the skin for purging, relaxing muscles and reducing swelling. Don't guarantee it as a hangover cure, however.
If you're on water restrictions and using bathwater as greywater, epsoms are perfectly safe, unlike bath oils, foam baths, etc.
Hope this helps.