I've recently had some very similar work carried out and used David O'Doherty. If you are looking for someone who is not only 'conscientious and reliable' but a great tradesman who takes pride in his work I suggest you get him in for a quote. Whenever I've used him his approach has always been honest and very competitive and he never attempts to persuade you to have work done that doesn't need doing. He also uses some other great tradespeople when needed including a great carpenter called Bela who fitted my kitchen.
You can contact David on: 07830119421.
I can recommend Radek Tober - if you search for his details on HoL you will find he has lots of recommendations too. Good luck with all the work!
We used Bela too for fitting our kitchen who is fantastic. He came through Gavin Hunt (who is a local Harringay'er) who did the building work for our kitchen including fitting some RSJs etc. Thoroughly recommend both of them. DM me if you want Gavin's details.
We are looking for similar work - do you have Gavin's contact?
I just wondered who you went for in the end?