ClaverdonPrimary

I'm a great fan of Trumba and am exploring the features a bit more. I've tried setting a map link for an event but I have a bit of a problem. I'm in the UK and I've entered the post code for the map link. However, all the services show the 'pin' a few hundred yards away from where I want it. When I've used a location map for the web site, I've started with the post code and then refined it so I now know the longitude and latitude for where I want the pin. Can I do this with Trumba?