A few years ago my neighbour had an extension built at the side of my property. When the builder came to finishing off he couldn't access the far corner because I had an old shed there that was very large and well fixed into the ground. We agreed that, as I was going to replace it soon, he would come back when it was demolished. I got rid of the shed but my neighbour didn't bother to contact the builder so eventually I put a storage unit there to cover the corner and forgot about it. Now I'm about to put a more permanent structure there and would like to finish off that corner (new owners of the extension who didn't know all this are asking if this could be done before I erect my new shed). Is this a job for a professional or shall I just offer to fill and render it myself. Not too bothered about the pebble-dash etc. as it will be hidden. How should I proceed with the job?