Must admit all that with the graphs went over my head 
I now have another issue, and would welcome comments.
I've breadboarded the chip neatly, and tested it using the example blink and fade examples - worked fine. I then breadboarded the 1307 RTC chip and uploaded the sample code below (found on this forum)
/*
*
* Read and set through serial port demo sketch for DS1307 I2C rtc clock
*
* DS1307 library provided by mattt & D.Sjunnesson, corrected by bricofoy.
* See DS1307.h for more details.
*
* This exemple code is under GNU GPL
*
* (c) bricofoy 2012
*
*/
// This is for compatibility with both arduino 1.0 and previous versions
#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif
#include <Wire.h>
#include <DS1307.h>
void setup() {
 Serial.begin(9600);
 use();
 read_RTC();
}
// use explanation message
void use() {
 Serial.println("\nUSE   : u U r R h[00-23]m[00-59]s[00-59]j0[1-7]D[01-31]M[01-12]A[00-49]");
 Serial.println("\nEXEMPLE : h09m35d03 set time to 09h35 and day of week 3 (thuesday).");
 Serial.println("\nCommands : h** : hour, m** : minutes, s** : seconds, d0* : day of week");
 Serial.println("     M** : month, Y** : year, D** : day of month.");
 Serial.println("     r stops clock, R starts it. ");
 Serial.println("     u or U shows this message, all other caracter shows time.");
}
// DS1307 time read function
void read_RTC() {
 Serial.print("\nActual time : ");
 Serial.print(RTC.get(DS1307_HR,true)); //read the hour and also update all the values by pushing in true
 Serial.print(":");
 Serial.print(RTC.get(DS1307_MIN,false));//read minutes without update (false)
 Serial.print(":");
 Serial.print(RTC.get(DS1307_SEC,false));//read seconds
 Serial.print(" ");        // some space for a more happy life
 Serial.print(RTC.get(DS1307_DOW,false));
 Serial.print(" ");
 Serial.print(RTC.get(DS1307_DATE,false));//read date
 Serial.print("/");
 Serial.print(RTC.get(DS1307_MTH,false));//read month
 Serial.print("/");
 Serial.println(RTC.get(DS1307_YR,false)); //read year
}
// set clock values
void write_RTC() {
   char value=0;
   char command=0;
   command = Serial.read();
   delay(50); //delay to allow good serial port reading
   value=byte((Serial.read()-48)*10); //-48 becaus ASCII value for 0 is 48, 1 is 49, etc and *10 because we read tens first
   delay(50);
   value+=byte((Serial.read()-48)); //and then we read units
   switch (command) {
case 'h' :
 RTC.set(DS1307_HR,value);
 Serial.print("hours set to ");
 Serial.println(value,DEC);
 break;
case 'm' :
 RTC.set(DS1307_MIN,value);
 Serial.print("minutes set to ");
 Serial.println(value,DEC);
 break;
case 's' :
 RTC.set(DS1307_SEC,value);
 Serial.print("seconds set to ");
 Serial.println(value,DEC);
 break;
case 'D' :
 RTC.set(DS1307_DATE,value);
 Serial.print("day of month set to ");
 Serial.println(value,DEC);
 break;
case 'd' :
 RTC.set(DS1307_DOW,value);
 Serial.print("day of week set to ");
 Serial.println(value,DEC);
 break;
case 'M' :
 RTC.set(DS1307_MTH,value);
 Serial.print("month set to ");
 Serial.println(value,DEC);
 break;
case 'Y' :
 RTC.set(DS1307_YR,value);
 Serial.print("year set to ");
 Serial.println(value,DEC);
 break;
case 'u' :
case 'U' :
 use();
 break;
case 'r' :
 RTC.stop();
 Serial.println("Clock stopped");
 break;
case 'R' :
 RTC.start();
 Serial.println("Clock running");
 break;
default :
 break;
   }
   read_RTC();
}
void loop() {
 if (Serial.available()) {
  write_RTC();
  }
}
This is (if I ready the details correctly) will display the date / time via the serial monitor, which is fine as I don't have an LCD hooked up yet. The code compiled and loaded without error, but when I launched the serial monitor I got the message that the port was in use and I needed to close other applications. So I tried uploading the basic blink example and got the same message... it seems that the code running won't free up the com port 
Any suggestions ?
Malcolm