SD is currently showing 127.11 as the Oxford Approach frequency. When I called yesterday (1st April) there was no response on 127.11, but 127.75 was working as before. According to the AIS spreadsheet, Oxford approach is still on 127.75 up until the 11th April. http://www.caa.co.uk/uploadedFiles/CAA/Content/Accordion/Standard_Content/General_Aviation/21032018%20833_AIP_Supplement_Data(1).csv

I'm afraid the rollout of 8.33 frequencies is a mess, and is not necessarily coinciding with the international standard AIRAC update cycles. We are doing the best we can, armed with a spreadsheet and unofficial words with airfields supplementing the normal AIP.