Hello and welcome to SayNoTo0870.com.
The best I can do is from the surgery's
contact page. 0870 111 4502 is given for "international" callers and quite a few landline providers charge 0870 the same as 01/02/03, including them in packages on the same basis. This may change in the future (0870 may become more expensive).
You will obviously have to check with your provider as to whether this is the case. If calling from a mobile, this may or may not be cheaper than the 0844 number.
If you let us know your provider and tariff/package, then we can see if we can find the pricing information online.