I recently moved to Wheaton from another Maryland suburb and found a delightful Scottish pub--the Royal Mile Pub--very close to my new apartment. It is right off Georgia Avenue, near the University Boulevard intersection. Its decor and food are quite authentic, and what my friends and I have sampled so far (baked brie, fish and chips, Welsh rarebit, Scotch eggs, and the chicken sandwich) have been absolutely delicious.
However, I must warn that the service, both times I was there, has been extremely slow. I had the same waiter each time and don't know if the problem was with him, or if the kitchen is also slow. The second time I was there, we were literally the only people in the pub, but it took over an hour to get our food--and there were only four of us! He initially only submitted our order for appetizers and didn't even submit our order for entrees until we reminded him that we were ready for our food. This further slowed things down. We had to ask him to refill our drinks, too, as he never once checked on us.
So, while I highly recommend this restaurant for fantastic Scottish food and ambiance, be prepared to spend an entire afternoon or evening there!