Hi RMcD94 - you inspired me to come out of lurking as I'm possibly your nearest ERE neighbour (I'm in Glasgow) and at 28, I'm just about young enough to remember school ;)
I like your enthusiasm, but I would advise caution on your expectations. $1700/£1062 a month is very high, well beyond the usual ERE range in my opinion. My basic expenses (i.e. rent, tax, utilities and food) in a nice suburb of Glasgow are £550/mth if I cut back to the bone). The rent and bills are split with my fiancee, but I could keep them at this level by renting a bedsit etc. if I was single. ERE strikes me as a combination of low expenses, voluntary simplicity and high assets to have the time to do what you want to do. It's not about supporting a middle class lifestyle as if by magic!
Also, unless I'm doing the maths wrong, your 'number' would be £420,552 assuming a safe withdrawal rate of 3% (£1062*12*33). This equates to roughly $675,000 for all you lovely Americans.
Average salary in the *UK* is lower than you think (£24,024 in June 2011 (roughly $38,438). I got this from the Office of National Statistic's Labour market statistical bulletin. The median figure is probably more accurate (we're not all software developers and fund managers) and this figure was £21,221 ($33,953) for *2010* (see ONS' ASHE (Annual Survey of Hours and Earnings) for 2010. As well as that, average earnings in Scotland are lower again, as the UK figure includes London etc.
Assuming you can get a job that pays the average wage, you will take home roughly £18,467 after tax and NI. With a 75% savings rate it will take you 30 years to reach your target. Of course you will get pay rises over time, but getting a job that pays even the average will take a lot of work. There are relatively few careers that will take someone straight out of school and pay them £24k. It took me until I was 24 to earn this and while I'm not a crazy motivated genius, I have good qualifications, a good CV and not the worst career history ever.
Some things to consider: if you're serious about ERE, start planning now. If you don't want to go to uni (arguably the easiest way/a prerequisite to getting into a highly paid salaried job for most professions in the UK), you will need to find a well paid skilled/non academic post (no slight to any careers, we all do different things for a living!) The sorts of things to consider looking at your studies to date might include engineering type jobs/subjects (for example, Scotland still has a good amount of offshore posts in oil/gas extraction and increasingly, renewable technologies). If I were you (and these sorts of jobs appeal), I'd start researching apprenticeships with some of the larger firms and pestering your school careers advisor for information.
On the other hand, if you do go to uni, there's nothing to stop you applying for student loans, investing these to kick-start your ERE progress and working hard to get summer placements etc. as you study.
Whatever you decide, best of luck - great to see someone considering the alternatives to a traditional career route so young!