There is no obligation for any patient to have a particular treatment if they decide not to have it. If a patient, in full knowledge of the facts, decided that they did not want to have, say, the temozolomide because they knew it suppresses T-cell function and may, therefore, decrease the efficacy of DCVax-L, I doubt very much that they would be disqualified from having the DCVax-L on the NHS, especially if it saved the NHS money by not having to prescribe temozolomide (over £4k/month).
I think that politically it would be very unlikely for patients to be denied a life-saving treatment (or having to "go privately") to have that treatment because one of the components of the S.O.C. is a known suppressor of that new treatment which is the most effective component of the "new" SOC.
Why do you think that patients in the placebo-arm who relapsed in the trial and then received DCVax-L much later than those in the active-arm group, did better? They were not receiving temozolomide when given DCVax-L.