I don't want to put you off knife making, the more the merrier in my book, but I think you could probably do with lowering your sights a little, or a reality check.
Everyone who starts making knives thinks that their first efforts are fantastic.
But, unless you are a genius with extensive machining/craft experience, plus wide exposure to and use of knives...they probably won't be
. Not really. Not from a commercial stand point. It is unlikely that anyone will tell you this to your face. Either the people you show will be ignorant of the quality available in the market (happened to me, happened to a friend and can be rather a bad thing) or they will want to encourage someone they see as having promise,
or they just won't want to be rude.
I was told by quite a lot of people that my early knives were great.
They weren't. :theyareon Some I was able to sell for what I thought they were worth. I don't think that I will ever be able to thank the people that bought them enough. Others I have never been able to sell. If you spend 10 hours on a knife, and can only sell it for £50-60 its not a great way of making money. If you do it because you like it, and you find that you are running out of places to stash the knives that you were going to make anyway, selling them for whatever you can make is great. If you are planning to make the knives with the intention of selling them and making money...thats a little harder.
As has been said, to do that here you would need to become a "Maker". It would also be a very good idea to familiarise yourself with the rules of advertising, and even more important, with the laws of knife use and carry within the UK. If anyone should know that stuff its someone making knives, if only for self preservation.
Design, fit, finish, and heat treating are things that come with practice and time.
I have seen a lot of knives sell poorly, or not at all, because basically the maker had a thought along the lines of..."Hey, that knife looks cool, I could make one of those, its going to be a challenge but it looks really interesting." They make it, and no one buys it because the maker didn't have a clear idea of what it would be for or how to use it. Designing with a clear purpose in mind is important to selling knives. It doesn't matter how well it is finished or heat treated if no one can imagine what they will really use it for, unless it is absolutely a piece of art work.
Many times I have seen the first half dozen knives, sometimes more, that a person makes are all derivatives of someone else's designs. Nothing wrong with drawing inspiration from the work of others, I am very guilty
However. in the early days it does seem that the inspiration is drawn from a very narrow range of reference (hard to avoid except by the application of time in research) and that often there isn't yet a full understanding of why a design looks the way it does, or why certain features are there. This doesn't just apply to knives. If you know why every curve is there and how it will work every which way, it shows.
Taking your question on what people want in a knife. There are hundreds of discussions on this all over the internet. There are loads of threads here, on British Blades, on Blade Forums, Knife Forums, and Knife Networks. I am sure that people will tell you what they like on here, but there is so much more information out there waiting to be sifted. If you are serious, you gotta get reading. There is everything you need to know about steels, sawing, filing, grinding, drilling, heat treating, hand sanding, polishing, glues, pins, handle materials, finishes, and sharpening.
There is even a particularly good thread here which might be worth a read:
Fulltime Makers: Fears and Satisfaction
Sorry if it sounds like I am trying to put you off. I am not, but I would like you to avoid some of the pitfalls that I have hit, and make better progress than some of the other folk I know who have started in on knives for fun or profit.
Best of luck