I do this quite often when traveling. The best option can only be selected based on the length of stay and the volume of calls. For a short stay and lower call volume, any of the suggestions in the thread are fine.

For a longer stay or heavy call volume, I would do the following:

I would sign up for a VOIP service with unlimited calling....I use Teleblend as they're the cheapest but Vonage has cheap intro-prices (for a few months) on their unlimited world-calling plans and you can pack the handy dongle to make 'local' calls while abroad. MagicJack's int'l rates are very uncompetitive, especially to mobile numbers in the UK. Just cancel Teleblend or Vonage after the trip if no longer needed.

Forward the Verizon number to the Teleblend or Vonage number, then forward the VOIP number to the UK cell - unlimited inbound calling for free (except UK mins used) and a Vonage dongle for making 'local' calls back to the US from your computer while traveling abroad.