I am trying to re-vamp the kitchen on minimal budget, painting cabinets, new glass splash back and I really want to replace the mixer tap. The base of the current mixer looks quite large though and goes directly into the sink which we are not replacing. So if I had a new mixer tap with a slimmer base the hole would presumably be too big? Can I get something to cover the gap, or does the new tap need to be exactly the same dimensions at the base?
I think it's a fairly standard thing. Just replaced mine and there was no problem with the hole in the sink. It may be that your existing tap base is wider than it strictly needs to be.
Depending on whether you have local isolation valves and bits of flexible pipe, mixer taps aren't difficult to remove to check the hole size. There'll just be an 11mm(ish) nut tightened against the base of the tap on a threaded bar sticking out of the bottom of the tap behind the two water feeds. You might need to get hold of a box spanner to loosen it.