If you're on a work visa at the moment, you won't be able to qualify for citizenship using form UKM yet... unless you qualify for UK citizenship by other means, such as through your parents (but in that case you wouldn't have need a work visa in the first place).
If you don't already have a claim to UK citizenship through your family, in order to qualify for citizenship, you need to hold ILR (permanent residence) first... which you can apply for after spending 5 years on a work visa and after passing the Life in the UK test (and meeting the other requirements).
Then after you have been granted ILR, you have to wait a further 12 months before you are allowed to apply for citizenship... so that's 6 years after moving to the UK (5 years on a work visa plus 1 year on ILR).