Dan, those of us who call ourselves artists really, really, really want you to go back to photography.
Ha!
It does look like you've already given the essential time. Before I changed my spectacles to take a closer look, I reached for my keyboard to ask if you hadn't sent the photo instead of the painting. Just as well I took a second look before I made a fool of myself.
Whatever they say in public, lots of painters work off photographs. They wouldn't earn a living if they waited for the sun to shine! I always take a backup photo in case the painting session gets rained out or just clouded over. One of the reasons that I paint pretty small en plein air is that so often the weather refuses to cooperate.
Mind you, sometimes that can be amusing. In the spirit of the thing, as lecturing at college from the galleys of one of my books, I dropped the lot, and just continued reading from the first galley I picked up, regardless of subject, one day I was painting what I took to be the gatehouse of a grand estate just around the corner from my house and when it started raining, after putting the cover on my precious Brooks saddle, carried straight on, the rain adding a certain vagueness to the painting. The owner came out and, mistaking me for an itinerant painter, said, "How much is that painting?" I said, "A hundred euro," which he took out of his wallet and gave me. I gave him the sagging wet postcard and said, "Be careful how you dry it." He was very brassed off. "You've made my half-million Euro house look like a tumbledown shack!"
Seriously, if you've already decided to go back to photography, then it isn't worth investing in better materials. You've already proved that you can do the job right, or almost right, with what you have. You already noticed the one thing I'd do differently, which is to make the outlines lighter in pencil (to be partially rubbed out when the paper is thoroughly dry -- it won't harm the water colour), or redesign the image to separate blocks by colors and contrasts; that may seem like a mountain to you, but next time you'll know. I'd also not even try for realism, because a camera will always do it better, and I'd bring the painterly aspect well forward from where you have it in the hazy distant background; for instance you could leave part of the church unpainted, a common trick that is common because it works so amazingly well.
You might want all the same to read up about materials for watercolors, because they do make some things easier (for instance professional paints of all classes are much more heavily pigmented than the student grades, and professional grades of paper offer a smoother finish which scans well, called "hot press" or simply "smooth", but makes it more difficult than cold press -- dimpled -- paper to control the paint) but at much more than marginal extra cost.
The best guide is Bruce MacEvoy, a chemical engineer from the reprographics trades, who for people like us makes a much more credible fist of technical matters in art than the arty-farties; he's a pretty good painter too. I recommend you start with the basic palette he recommends, called the "secondary palette" which is only six colors plus (not essential but convenient) two earths plus (not on dear Bruce's list, but the secret vice of many, many professional painters) a tube of good quality white gouache for highlights and mixing opaque tints, nine colors altogether, the price of which will be enough of a shock. See
http://www.handprint.com/HP/WCL/palette4e.htmlAll the applied technical information on watercolor pigments you ever wanted -- my bible:
http://www.handprint.com/HP/WCL/waterlk.html and note that the same pigments are used in all artist's paints.
There's much more to McEvoy's site than information about watercolor materials,
http://www.handprint.com/HP/WCL/water.htmlwhich you can find by searching backwards from this watercolor index.
Actually, while I'm sure there's nothing wrong with your photograph from which you made the painting, I think the painting is more interesting than the photo could ever be -- except to a cyclist, who has a different outlook on different interests. A painting says infinitely more about the painter than a photograph does about the photographer.