Legally there is no limit.
The UK is a part of Europe.
That depends on what you mean by "near." Basically, France is between Spain and the UK. Spain is much nearer to the UK than to Australia, but much farther than France, Portugal, or Morocco.
the quantity of tobacco can legally bring in to the UK from Belgium
Some!
Yes, as long as it is in your suitcase. not if it's in your hand luggage i don't think :)
Free if the dog has wings!
There is no estimate of how much money that is allowed to be taken in the airplane and yes, you can bring 100 million to UK for your business.
Milk or beer.
Spain is an hour in front of the UK
Spain is larger physically, and has a larger population than the UK.
Root Beer Although not many places sell it, and pretty much unheard of in a restaurant. Sainsbury's and Asda supermarkets sell American and Australia Root beer but mainly only in the big stores.
It is about nine pre-decimal pence (d). It is equalled to£ 1.12 today.