I have excel spreadsheet that I need improving, and whistles and bells added.

I have a number of clients in a specific business sector. I prepare accounts and tax returns for them. They either populate a spreadshhet or I do this for them. The spreadsheet then produces reports and a tax computation. I want this to be easier to use and look more professional. I also don'twant clients to be able to change or copy or adapt.
It would be useful if you were local to the Wirral as I may also like some one to one excel training.