Jcar
to get the best look at Stonehenge I would go online and book an
Inner Circle Tour.
Viator has good information.
You can do it on your own, via rented car/taxi public transportation. You can take a train to Salisbury and the there is a "tour bus" from there that takes you to the stones.
When I was a child, we just parked the car near the stones and I ran up freely around the stones, able to touch them etc.
Then people lost their marbles.. they HAD to carve their initials into the stones. So a fence was put up around them. So these days you can walk around outside the fence. But there are still a few of the "Inner Circle" tours offered. And If I was going there for the first time, I would shell out for that tour.
That being said, remember that although these are by far the most impressive stones, there are a lot more circles dotted around the British Isles.
About that beer.. The White Star Tavern does serve some gluten free beer.. so.. Cheers