I think you need to consider your plans carefully. Like Spencer, I'm a UCL grad and I'll give you some of my thoughts and experiences.
Clinical medicine isn't one of those cut and dried things where you can think, "I'll devote x amount of time here, and then deal with my other priorities afterwards," it's really one of those things which you need to devote time and flexibility to - anything can happen, opportunities can crop up at unexpected times and the only way you're going to get a lot out of it is to be on the wards.
People are unpredictable - I once arranged to have dinner in the centre of town with a friend, and I had a late afternoon ward round. As time approached for me to leave, we went to see a patient who was experiencing a manic episode at the time. They talked non-stop for an hour and a half. I arrived an hour late for supper, my friend (also a medic) understood, but it's just one of those things. You may be just about to finish and an opportunity arises to work on your clinical skills, or a baby is about to be born etc. sure you can read books, try to see patients in an arbitrary time period, but people just don't work like that, sometimes patients don't want to see you, or there aren't many available to clerk, or you have teaching - that's just the nature of the beast and I think you'd be doing a disservice to yourself to try and box everything up neatly to make things manageable, it just doesn't work like that.
Yes, consultants may not be around all the time, but they're not stupid, and sometimes you may have to spend an afternoon in theatre with them just to be 'seen' or they rely a lot on hearing from other staff members to let them know who has been showing up or not.
As Spencer said, you pick up on so many subtle things that just aren't covered in the books or learned by yourself - a reg may give you a hint to improve your clinical examination, or colleagues can give useful feedback - so I'd advise caution on spending additional time before term starts, because you may not be exposed to that, and examiners can tell who are the students who spent time on the wards with patients as opposed to those who just showed up at the last minute.
I'm not saying neglect your business entirely, I really admire the fact that you've set one up, but I think you need to think about how you can manage it around clinical medicine and not the other way round.