I got mine online from swell uk, seemed to be the best price at the time and is decent quality. I usually suggest that people keep fish suited to their water - but yours is very hard and your options are quite limited. One option may be to mix your water 50:50 with RO water but you need to think about the cost and convenience.
My local maidenhead aquatics sells RO at £3.50 for 25 litres (don't buy the jerry cans from them they are much much cheaper on Amazon ). I also have very hard water and did this for a while. Since my weekly water change is 200 litres I got fed up of lugging 100 litres per week from the fish shop and ended up getting my own RO filter. That is not without a cost though. Our water is metered (a lot is wasted when you make RO) and it takes me a couple of days to refill my containers after the weekend.
Thanks, again that’s helpful. Tank I’m looking at would probably be ok getting the 20kg bag.
I’m gonna go into my lfs on Saturday with a water sample so they can test it for me. Least I’ll know definitely what I’m up against and that may influence my decision. So desperately wanted a bristlenose but wouldn’t want to go down the route of buying specialised water or buying RO equipment.
This website has certainly helped me so far