That's categorically not true. A huge proportion of medical students have a gap year before they start; some of us have a few. Probably about a third of my cohort came to Medicine off the back of a gap year/another degree. If it were a smaller proportion, I'd be tempted to say we were exceptions to the rule, but with those sorts of numbers it's difficult to see time out being construed 'unfavourably'.
OP - sounds like you've got a lot of the boxes ticked already. What's made you decide to change to Medicine though? I'm not of the mindset that says only people who've been thinking about becoming a doctor since they were six should apply (far from it; definitely wasn't the case with me), but there are better and worse reasons to study Medicine.
If you're sure this is what you want to do, I don't see why you can't apply this year. Get some more work experience, and try to work out early which universities you'd be looking at, so you know whether you'll need UKCAT/BMAT/both. Good luck.