A belated welcome

Good to see you have adopted a responsible fishkeeping approach, putting the life of the forthcoming fish first, rather than a blase approach of "hope for the best". Your forthcoming fish is going to have a lovely new abode – your tank looks great!
It’s disappointing that some/many LFSs don’t acknowledge the fishless cycling approach as a “tried and tested”, fool-proof method. While it is in their interests to sell products, it would be better all round if they acknowledged its merits and encouraged those who adopt that approach. There will still be many customers who don’t have the patience to see it through and, in those cases, a bottled bacteria product is a better approach than a fish-in cycle with no such product. As I understand it, though, the evidence of effectiveness of these products is still quite varied – some folks have a successful cycle, others don’t; it depends on various aspects such as storage from manufacture to use, ingredients of the specific product, etc.
Your water supplier’s website will be a great place to get details of your specific postcode’s water hardness/softness – in CaCO3 mg/l or German degrees hardness and PH. However, Fishtales mentions some discrepancies between hers and her test results. Worth looking at both, though.
As for ammonia, you may already have got the Dr Tim’s. Another popular option for fishless cycles is Kleen-Off.
As for discussions about different LFSs, chains or otherwise, this is something we've discussed on here fairly recently. Many of the chains are franchises, and, even within that and even within stores, there is huge variation - often it comes down to the level of interest of a particular staff member. As it happens, I was very impressed by a local PAH during a visit back in Sept and their various processes for the welfare of their fish across the chain - for unrelated reasons, I hadn't been in one for 5 years but was aware back then of the variation from store to store, and this probably still applies, although they have streamlined their welfare processes re checks and monitoring of the fish and associated record-keeping, etc. As for independent LFSs, there aren't that many around these days, it seems.