I won't bump your other topic asking about Britain, but I'll say this here anyway.
You won't be able to avoid tourist things in London.
But that's not a bad thing. Because the tourist things are great.
Try Madame Tussauds waxworks, Natural History Museum (free), Tower of London (see the crown jewels), London Eye (this will be very very busy, so maybe give it a miss).
Also, you'll want to get around via the Underground. If you're in London for a while, and travelling quite a bit, then you'll probably want to get an Oyster card, which you can top up, and use. Rather than buying specific tickets each time.
The Welsh are legendary sheep shaggers though so he might be right at home in the UK.
It's approaching lambing season. The welsh tend to lay off of them this time of year.