-hike in the Moors Great idea!
http://www.ramblers.org.uk/ and
http://www.naturalengland.org.uk/ourwork/enjoying/countrysidecode/default.aspx have some helpful info. Be aware that it can get muddy, so good boots and waterproofs are essential. Very good maps are available published by the Ordanance Survey- often referred to as OS maps.
-eat really good food- There are plenty of places you can get that! Go for independent places, there are lots of good restaurants, tearooms and pubs serving food.
see the beautiful countryside- Plenty of that around! The North York Moors are spectacular, and the Yorkshire Wolds are worth a visit too. Both are easily accessible if you are staying in the Thirsk area, and the Pennines aren't that far off either. The Plain of York is a bit odd- very flat and not quite what you'd think Yorkshire was like.
visit the World of James Herriot That's in Thirsk
http://www.worldofjamesherriot.org/-see unique places I'll do a list in another post for that.
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avoid large crowds Some places are best visited midweek- I'll make a note about those.
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SO wants to drink in a pub There are plenty of those! You go to the bar to order. Beer is served by the pint or half pint, although there are plenty of other drinks available of you don't fancy beer. Then you take your own drinks over to a table. You don't usually tip the barman, but you might say "And get one for yourself", and they take the cost of their own drink out of the money you give them. He might like visiting the Black Sheep Brewery at Masham. Also, lots of pubs serve food nowadays.
One other thing has occured to me- credit cards are widely accepted, but usually only Visa or Mastercard. Amex isn't widely taken here, so you might need to make arrangements for that. There are cashpoints in most places, even in some villages.