It's not quite correct and the two correct translations are:
Lass mich darüber nachdenken.
Gib/Lass mir etwas Zeit, um darüber nachzudenken.
Nachdenken is here more suitable then
denken. The latter is a
general word for
to think, the former means specifically
lass there is always an infinitive without
- In the second sentence there is of course
mir (Dativ) instead of
As pointed out by Em1 (thanks), in my second example there is a verb
lassen followed by
infinitive + zu which seems to contradict the point 2 above. The reason is that in this case I am using a
um...zu + infinitive construction which must contain
zu. I think in this respect the use of
lassen is very similar to the english
Lass mich nachdenken - Let me think
Lass mir Zeit, um nach*zu*denken - Let me take some time, to think about it.