When people ask "in second year I got X as my average, can I still get a first/2:1", they are asking about 3rd year.
It depends how much your second year contributes towards your grade classification. If you get a first in second year, it is still possible to get a first overall at the end of third year - so of course you would still be able to get a 2.2 in your final year . People don't ask "how likely" because that is just down to the individual. It's more "what is the lowest grade I need to get to reach a first?"
If you achieved a 2.2 in second year, it makes it much harder to achieve that first in final year because of course you would need to get higher marks in general in final year