Lots of great advice given so far. I got my first bike last year and went to my local bike store and bought a Giant Roam 2. I'm based in London too and managed to get a good deal through the cycle to work scheme. If your employer can support you with that, it is worth a look.
I have had a slight discomfort in my wrist over the last few years and when I tested various bikes I found the suspension more comfortable. In addition, I found investing in decent gloves with cushioning was beneficial. I've since bought a cheaper full finger pair for winter and found decent cushioning was a must on the palm of your hands.
Another upgrade I made to my bike is adding bar ends. When out on the open road they are much more comfortable and I'm glad I made that upgrade.