Project 34365: part 198

我们去了野餐。 I suggest 我们有个野餐
昨天，它是个晴天。
我们Harrow-on-the-Hill。走了趟圈Harrow-on-the-Hill。If I'm not mistaken, Harrow-on-the-Hill is a swanky district not a hill or something that you can walk in a circle around it.  I assume you all went shopping etc there for the day.

Project 34365: part 198

我们去了野餐。
昨天，它是晴天。
我们在Harrow-on-the-Hill上走了一圈Harrow-on-the-Hill。

haha,did you enjoy your picnic, it's thundering outside...

Project 34365: part 198

我们去了野餐。 √

 
昨天，它是晴天。

昨天是个晴天。

I suppose you want to say:It's a sunday. ：）

我们走了一圈Harrow-on-the-Hill。

我们在Harrow-on-the-Hill走了一圈

Hope it helps ：）