Hi SC, one can still eat well cheaply in London, e.g. their
cornish pie is about £2+ and it's big enough to work as brunch. And
surprisingly, I find some of their groceries quite cheap (cheaper
than in Sg if you're earning pounds), e.g. a large pack of baked
waffles or some other pastry like thosai costs £1.80 which can last
for 3 meals! These were prices that I saw last Nov.
Stonehenge is good to see, just stand outside the fence and save
the exorbitant entrance fee. 
You can do the same for those Windsor castle, etc.
...just admire from outside. I like Bath...it's such a quaint town
with little houses build close together...it had a very nice Thai
restaurant many years ago but I'm not sure if it's still there.
Have fun! 
ps: sorry, I've no info on how to get to those
places, as I'd rented a car and drove out from London many years
ago.
