My Google apps timeline says I went to a postcode and stayed there for 3 hours when I never left my house which is 4 miles away from where it says I was it was in the middle of the night when I wasn't even on my phone I was asleep. But on the following date it says I was at my house from 1200am-135pm which was obviously the start on the next day and which means I was at both locations at the same time. Any light shredded on this would be great. Is there anyway to prove I didn't leave my house
Do you use your Google account on more than one device? Or do you turn off location and your cell data and connect only via wifi? If you were connected to WiFi on your phone, or another WiFi or ethernet connected device logged in with your Google account, Google may have assumed your location was the location of the IP address you were using (which isn't necessarily where the actual WiFi router/access point is). 4 miles away is about the right distance for say a cable broadband hub and the IP address location may have resolved to somewhere near the hub.
If you go to http://whatsmyip.org and click on the "more information" button, it will attempt to locate you via your IP address. That's likely analogous to where your weird Google location came from.