Not sure exactly what you are asking - are you talking about feeding your 12k into a regular saving account, say, 1000 quid at a time (that would generally be the max) vs putting all of the 12k in a fixed term deposit account?
Be careful when looking at the rates for regular saving accounts. You will see rates like 5% quoted which look higher than those for fixed term deposit accounts.
However if you put in 1000 each month into a 5% regular saver account for 12 months, at the end of one year the interest rate on your 12k will be approx 2.5%. OTOH, if you put in 1000 euro the first month and then 1 euro (if allowed) for the next 11 months, your interest rate on the 1011 quid will be very close to 5%.