Hue makes a B22 bulb in England, but I don’t think anyone makes the smaller B15 in a smart model–there’s not enough room for the radio.
http://www2.meethue.com/en-us/productdetail/philips-hue-white-and-color-ambiance-starter-kit-b22
In the UK, B refers to the type of socket fitting (a B is a push and twist in rather than just a screw in), but you still need the number to know the size of the base.
If you take one of your old bulbs and look at the base it may have the size code printed on it.
As @brumster mentions, converters are inexpensive and will work fine, but make sure you get one that converts to E27, not the E15.
Here’s a converter for the smaller B15 size to the typical smart bulb size of E27:
https://www.amazon.co.uk/Lamp-Socket-Adapter-Converter-Bayonet/dp/B00IXQ7VB4/
And one for the larger base
Of course, these converters will be very obvious in the sockets if this is a chandelier type fitting so that’s another thing to take into account. If you want to keep the same fittings, you might have to use an in wall relay rather than smart bulbs, but that would require electrical work.