He had plastic bags on his feet when they were in Whitechapel. I don't think it's been said they'd been sleeping rough or walking through fields or woods before then, except for a short walk across a field after they abandoned the burning car. NFCI seems a strong possibility though.
The question is how does whatever's wrong with his feet play in the trial. It could go like this: she was in such a state, even more so because of his illness, and their relationship is one in which she mothers him a lot, blah blah. (That last bit may be considered a trifle weird given that he's a lot older than she is, but it's not criminal, and given that he was in a US jail between the ages of 14 and 34 he may well be less than normally mature in some areas of his persona.) Got to wonder how far the crown will get if they use the defendants' continuing to hide after Victoria's death as support for their case. Say for the sake of argument they're not guilty. Then she would have been in a right state, or at least that's reasonable to suppose, unless she is Cruella De Vil. Are their known actions consistent with this supposition, or do they totally blast it out of the water as being as near as it can be to impossible? And that, ladies and gentlemen of the jury...
ETA: Cruella De Vil would have had no difficulty disposing of the body. Seagulls would have helped her if called upon. Cliffs, the sea. She'd have thought of something. She wouldn't be in a state.
ETA2: I wonder whether the prosecution are even going to mention his feet? If they don't, it could become a defence issue, and we'll have a position where (what may be considered) important colour to the story has been brought to the jury's attention by the defence.
ETA3: In an earlier court appearance, didn't he have a jumper or coat pulled over his head, or am I misremembering?