I'm concerned about feeling the join of a zip and link mattress

Hi
We are planning to buy a kingsize bedframe with a slatted base which recommends a mattress size of 150 x 200cm. Would a kingsize zip and link mattress fit onto this bedframe?
I'm concerned about feeling the join of the two mattresses butted together; will a topper eliminate this feeling so it feels like one whole mattress or will the join still be noticeable?
Thanks
Jenny