I just returned from a 10 day England trip with my family. My son and I used the CityMaps2Go app and it was a lifesaver! You get 1 free map to download. Make sure to download the map so you can use it without wifi or cellular service. Before we left, I marked all the places we wanted to visit and possible restaurants. The app rates many of the restaurants. You can add places. For example, there were specific Harry Potter spots I wanted to visit so I just added them. I went ahead and purchased the premium app for $30. I felt it was worth it for me because even though I was on airplane mode the whole trip, the app showed my location at all times. My son is better at reading maps so he was great with the free version.
I'm sure there are other apps which are similiar. I had seen on this forum that someone else recommended CityMap2Go so I tried it. It was nice not to carry around a paper map. I also used it in Winchester, Portsmouth, Bath and Windsor.