Noticed an update to vertsms today and installed it, found I had the same issue in that only numbers with the country code added were sent. Seems to be a strange issue with some reporting this, some reporting the opposite. Numbers entered into the native SMS client both with and without country code send as expected. It's an odd issue.

If it persists through to the final release, i would be tempted to rewrite part of the coding to replace numbers added from contacts beginning "077" with a UK country coded version "+4477" before sending. (To use on my own handset obviously, I dont mean as a general feature request )