It seems to me, we would be better of buying 14 twin engine C27Js to operate alongside our A400's and C17's.
Too much duplication of capability with C130J and larger A400. Added to this the C130J will require considerable expensive work to guarantee it's service out to the 2030's, i.e wing centre box and outer wing replacement in the relatively near future
Better to trade them against new C27J's, to give us a balanced fleet again when all the A400's have been delivered, hopefully also pick up 8 additional unwanted Germanand Spanish A400's for a considerable discount and 4 more C17's, secondhand from the Americans.
If we (the UK) are serious about expeditionary warfare in the future, we better have the Tactical and strategic airlift to make such operations viable and sustainable.
Just a personal perspective..