Do not lie to your probation officer. If you don't have the hours done, then call him him tomorrow and ask for an extension or complete the hours before the deadline. It is the only way. You would be in contempt of a court order otherwise.
A lawyer cannot assist you in defrauding the court. If you present a false record to your probation officer, there is an extremely high risk that you'll get in far worse trouble than you are in already.
Don't even think about lying to your probation office-do as other counsel suggested. Either get the hours done over this weekend and before the 26th, or ask for an extension of time to finish them up.
Do not lie. Do the community service this weekend. Four hours is not a lot. There is no real benefit to lying about your community service.