@Dave7 - I answered your post about bedding plants in DIY. I didn't want to rattle on but thought this might interest you and perhaps other gardeners in here.
The plants I listed are the traditional bedding plants and the core volume of every bedding plant grower's range. At the right time of year you will find them everywhere, shortages this year are a direct result of Covid-19 which hit just as growers reached peak production levels.
There are literally hundreds of other items we used to grow all of which were intended to increase sales by widening the range and extending the season. The current Aldi offering is a classic crop to extend the season. Offer exactly the same product as one offered in May but put 3-4 plants in a big pot so making it appear to be a different product. Nothing wrong with this and a very wide range of plants are grown this way for July sales.
The other major crop you will come across is termed Basket & Patio plants usually offered in 9cm, sometimes 10cm, pots. These are usually cutting raised items, bedding plants are seed raised, intended for use in hanging baskets, window boxes, patio planters etc.
If you want quality at affordable prices B&Q, Aldi, Tesco, Sainsbury and most major multiples are sourcing stock from the very best UK growers. I know who they are and I've supplied B&Q. It is though important to buy stock within 48 hours of it arriving in store. The store staff lack knowledge and interest to care for the product, customers scrabble through making their choice etc. It's easy with ALDI because it will be advertised in advance and every store will stock the product on the day, this isn't true for other multiples. I would be wary of purchasing from B&M, Home Bargains and Homebase.
I think you are within easy reach of Bents. If you want to use an independent garden centre Bents is a good choice but in their case you will pay through the nose, probably till it bleeds. This isn't true of all independent GCs and there are many very good ones.
Hilltop GC, Shilton near Coventry is one.......just thought I'd chuck that in for one of our number. The brothers who run this GC are top drawer and really care about what the do.