This article “Could e-voting be on its way in the Uk?” would also be good news for British expats if implemented:
“Campaigners for electronic or e-voting say “digital democracy” is on the way in the UK. Although next year’s general election will be run using the traditional system, they predict a different landscape by 2020. “
However, without the convenience and encouragement of then actually being able to also e-vote on-line, the overseas voter is still faced with the problem of missing the election date deadline due to the delays inherent in the postal vote system, or finding a suitable UK resident to submit a proxy vote.
These are also reasons, including the 15-year-rule, for low voting rates among British citizens resident abroad.