is there any way to reset the time capsule for use in the UK
Sorry, but no. Apple sells different versions of their products in different parts of the world which are "regionalized". It is not possible to convert a product from one "region" to another.
The good news is that the Time Capsule will operate on 100-240 Volts and 50/60 Hz automatically, so it will work just about anywhere in the world if you have the right AC wall plug adapter or power cord for the country that you are in at the time. A voltage converter is not needed.
At this time, European countries in general do not allow the higher 5 GHz channels that your version is capable of using, so when you move to the U.K. be sure to set the Time Capsule to use one of the lower 5 GHz channels......36, 40, 44, or 48.
For a lot more information than you will ever need, see this article: https://en.wikipedia.org/wiki/List_of_WLAN_channels