I built this! (Learning faster than I thought possible  )
  )
Uses a lookup table:
| Items to replace | Replacement for each item | 
| 1st | First | 
| 2nd | Second | 
 = REGEX(cell,"("&TEXTJOIN("|",1,itemsToReplace)&")",                       # Find items to replace # VLOOKUP(REGEX(cell,"("&TEXTJOIN("|",1,itemsToReplace)&")"),   # Feed found item into lookup # replacementTable,2,0))                                                                       # Replace from second column # 
Any feedback welcome - I sense there should be a more efficient way of giving the Expression element of the REGEX.
Also - and this is important for my use case, i.e., cleaning punctuation out - I’m getting unhelpful results when I search for ( , ) , or ' ← should be serifed apostrophe, not straight.
And so far I haven’t tried a global regex - that might break it, though I think not unless there is more than one item found. So Southend-on-Sea will be ok, but 1st Floor 4-6 High Street will not?