Newbie - it sounds as if you are going to commit most of your available funds and a good chunk of change of future income to your plan. Good on you.
However, have you considered the rope around your neck, should you meet the girl of your dreams a year later, and have children. And need a bigger house / car for yourself and family. Raising kids for >20 years is an expense business.
The point is that non of us know whats around the corner. Once settled down and have a good idea of expenditure then it is much easier to plan for investments. I'm not so sure at your age and in your situation this level of fiscal commitment is a good idea. Don't forget that your primary residence has many tax advantages as free form CGT.
IMO you need to speak to an adviser, as you have so many questions in your head and this forum may not be the best way of sitting down and flushing them out.
