Posted: 28/10/2017 at 11:05
I don't think new shrubs would stand a chance of growing 'in the gaps'.
Without wishing to seem rude, I think youve been too timid with them.
In your situation what I would do is to cut the existing laurels back to below the top of the fence panels ... you could even go down to about one foot above the ground. The laurels will re-shoot and you can develop it as a proper hedge (from the ground up) or more like a 'hedge on legs' giving you some bare ground at the base if you cut them back to just below the fence tops.