You could try finding a personal trainer through Motivate as they are one of the largest in London and have lots of trainers with different specialities. Otherwise use one of the gyms in London like Muscleworks or Ripped gym as they will have trainers there. Depends whether you want to join a...
Dumbbells require the use of stabiliser muscles so you won't be able to lift as much. I usually use both barbell and d/b as this gives me a good mix of chest training
You should not just look at meal size but how much protein/fat/carbs you're eating too. McDonalds is high in sugar and sat fats so really avoid this if you're trying to build lean muscle mass. Did you not watch Super Size Me!!
I believe the lease on the premises is one of the biggest expenses on top of your taxes and of course the equipment (whether you choose to buy or lease it). Gyms can make money but you need a lot of upfront capital (or at least be prepared to borrow heavily) to get it off the ground.
I quite like the taste of brown rice (kinda nutty) but if you find it bland add some spices like tumeric or chinese seasoning. Depends what you're eating it with
I have never tried brown rice protein powder. I usually just go for whey. Are you diary or lactose intolerant? I have used Soy protein powder as a lactose alternative in the past as this has a great mineral profile not found in Dairy Protein.