Well I think generally little and often (or lots and often if you can) is better than a mega session less frequently. Whatever practice you do you should try and make it good practice so I think getting some 1-1 lessons is a good idea, in combination with group lessons. Most coaches are quite happy to teach relative beginners 1-1. I think around £20-£25 per half hour is average. Maybe choose a coach whose way of working suits you based on what you experience in the group lessons, maybe try to watch other group lessons too, to get an idea of the different teaching styles. It's good to want to forge ahead, but getting excellent basics will mean you progress much faster later on, so do put as much of your enthusiasm as you can into getting those basics really strong. I've been skating more than ten years and am still improving my basic edges, posture. Enjoy and good luck.