Hi Graham,
Firstly, you don't want to worry about speed too early in your running career. Speed training requires strong joints,so you want to let these get stronger over a few months before embarking seriously on speed training. Having said that, it you're really keen, you could start some fartlek, but just once a week, to minimise injury risk. Type the term into google, or the search facility here and it will come up with plenty of references.
Secondly, sounds like you may be starting most of your runs too fast. Hills inevitably slow us down, but in general, apart from the cool down, it's a good idea to get in the habit of running at such a pace that you finish more strongly that you start. (That takes a bit of pracitice and self -control!)
Good Luck 
p.s. 54 minutes for a 10k isn't a bad starting point! Well done!
Edited: 26/06/2012 at 14:43