A400M Usefulness
Declaration of interest: yes I used to work for Airbus but I am now retired.
Firstly, the original lease of the 5 C17s came under the STSA (Short Term Strategic Airlift) programme which was, indeed a competition between the An124 and the C17. The An124 was deemed to be non-compliant because it had no defensive aids and, therefore, could not be used in hostile environments (except, of course, when it is being chartered). As STSA was a stopgap it was always meant to be a lease arrangement and it then grew from there.
When the first 3 RAF A400Ms arrive they will be at SOC 1 standard, SOC 1.5 for the next 5 with other standards following. SOC 1 includes tactical capability inc some airdrop, and some defensive aids. SOC 1.5 adds AAR receiving and the rest of AD. National defensive aids are a national problem and all ac will be uprated as subsequent SOCs are cleared on the Airbus Military clearance programme. That said the SOCs are company solutions and contractual obligations but actual release to service is in the gift of the infamous Quintequeue which also needs to clear the specific RAF AD equipment and aircraft combination. If my experience with the J is anything to go by that could take some time. However, do remember who it is actually granting release to service (or whatever it is now called) and it is not Airbus Military.