change basin taps with mixer tap

At the beginning of the post you said you were not going to diy this and get a plumber in

Now your talking and asking as if your doing it yourself ?

With a bit of plumbing experience you can do it yourself, not that difficult

Choice of push fit connectora, really easy, compression or solder (bit more experience required)

Really anything can be done but sounds like you don't have a lot/any plumbing experience ??

If your insistent (or the missus) on a mono tap, get a plumber in, may be best option. Just source the tap and ensure it fits in hole, no drilling hole bigger, will end in tears (yours)