Phil,
Ignoring the drivel about relevant merits of degree vs DE, you need to consider what you are going to do if you don't make it as aircrew (many don't). Are you prepared to consider a career in the ground branches? If so maths/economics degree should demonstrate that you're trainable and most branches will be open to you. Something more focussed towards applied engineering is necessary if you want to go for Eng O (not physics or maths).
As to the year out - you look like you've done something reasonably worthwhile - make sure you window dress it properly, so you stand a fair chance.
Good luck