That is the way you learn, you make your best choices, and make adjustments. You made a 12 pound investment and you intend to live with it. I still say cut your loses and spend the 120 pounds for the Digitrax Zephyr (or something comparable). By the time you spend your weeks of wiring , buy the wiring (have you priced it lately), relays, more transformers, LED's, switches, etc. you might find you saved a couple pounds. But if you find that you didn't wire it as well as you like and you decide to change it, then you probably won't be ahead of the game.
If you go DCC, you run two wires and that is the end of it. DCC handles all the variations as fast as you can think about them.
By the way, you can use one of your transformers as a DCC controller with the Zephyr so two people can operate at once with no more investment. The other you can use to power your lights, switches, and accessories.
You are starting a project that will cost you 35-70 pounds a square foot by the time it is done. While it is good to save money where you can, don't save now in a way that will cost you later. Start with a good foundation.
Better yet, scale your layout way back, start with a small layout and make your mistakes now. Don't take my word for anything.
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Now on to the DC question.
Now you may wonder why you are not getting a lot of responses. For me, the reason is that since I don't know how you are going to operate, how things are going to move, what your spurs mean, what kind of traffic you intend, etc. I don't have a clue how to advise you.
But that is how you start. You devise an operating plan, and imagine how the trains are going to move. To me, that would be a first step. Once you do that you can start to see how the blocks shape up.
Do that, put in your best guess at how to arrange the blocks, tells us why you did it that way, and then maybe we can help you make adjustments
