MTT's hold bigger swings than STTs - so they are not necessarily the answer you are looking for.
Assuming you are a winning player, then it's just a question of "bankroll management" - how about playing STT's to a MAXIMUM of 5% of your bankroll - as your bankroll falls, then you move down the levels - as you win, you can play for higher stakes. If you lose your bankroll playing this way you need to rethink your poker strategy. I don't know how low
Betfair go, but
Blue Square go down as far as $0.10 STT's.
Have a think about playing in the PL Leaderboard games - only $1 or $2 to enter, but there is a lot of added value (paid out to the leaderboard winners) - problem with these is that the standard is higher than you would expect at buy ins at this level. And keep an eye on the diary published in here daily - plenty of great value freerolls with sometimes big prizes - a great way to practice and try things.
And reading i a great way of improving - especially if you have a little time on your hands to take advantage of it now....