New vanity unit in bathroom

[SilverLiningPlaybook]

The sink with vanity unit underneath needs to be replaced in an ensuite. I have no idea how to go about it. I have measured it, but am worried about ordering a replacement in case it doesn't fit. No bathroom showroom seems to do home visits or installations unless its a complete bathroom refit. Can anyone advise me what to do?

Measure the one you have and pick one the same size?
When it’s delivered a local plumber, rather than a bathroom fitting place, will be able to install it.
A handyman could probably install it tbh (DH did ours) but if it resulted in any leaks they may not be covered as no expertise whereas a plumber would.