As a new driver I am presently being told by my employer that if I reduce my wekend break to the minimum 36 hours break on 2 consecutive weekends then I only need to have a 45 hour break on the 3rd weekend.
I’m not too sure that if this is true as am also being told that if I reduce my weekend break to 36 hours I must have made up this 9 hour reduction by the 3rd weekend, ie the normal 45 hour break plus the 9 hour reduction = 54 hours.
If anyone with this knowledge could advise I would very much appreciate as I don’t wish to break the law.
Thanks … oooh me goblins!
Any reduction to the weekly rest period must be made up by the equivalent amount of hours taken in one block and added to a rest period of at least 8 hours. This must be taken by the end of the third week following the reduction -so if you reduce your weekly rest in week 1 it must be compensated for by the end of week 4.
In the scenario you outline where you have reduced to 36 hours on two occasions and you wanted to clear it all in one go, and wipe the slate clean, you would need a weekly rest of 63 hours - 45 hours plus 18.
However if in week three you take a 45 hour weekly rest you could count this as a 36 hour rest and use the other 9 hours to compensate for your first reduction. This would still leave you the 9 hours from your second reduction to account for and also the 9 hours from the 45 hour rest where you used them as compensation for week 1. Confused yet? 
Your boss isn’t wrong in saying you only need 45 hours on the third weekend, in fact you could do another 36 that weekend, but you have to keep a close check to make sure you are repaying the reduced hours.
Note that whoever is telling you that the reduction must be made up by the third weekend is giving you duff information as it is to be compensated for by the end of the third week following the reduction, which is the end of week 4. That is a very common mistake though as people just read the third week bit and ignore the word following.