You're missing something - you won't get a persoanl loan on anything like as good terms as a mortgage, in terms of interest rate.
Why don't you just ramp up the rate at which you pay your existing mortgage? - as and when you can afford the do it.
Check the terms of your mortgage - some of the less scrupulous ones only deduct any overpayments once per year - so the extra money is sitting there without taking down the capital sum.
I did this a while back with my HSBC mortgage - who calculate the interest on a daily reducing balance basis. I paid off �1000 extra here, �500 there - as and when I could afford it. Paid off a 25 year mortgage well inside 15 years.