In message , aka Robbie
writes
Ok I know it was my fault for presuming the builders would properly finish
off the garden and not taking the times to do it myself, but the turf in my
back garden is extremely uneven and bumpy.

Pity. It is a heck of a lot easier to get land level before you grass it
over.

Now I'm not after billiard table smooth, but a little flatter would be a
bonus. So what would be the best way of tackling it? Using a tuft cutter,
levelling the soil, then replacing the turf......

That method looks good on demonstration make over shows but if you ever
try it you will find it is extremely hard to add the right amount of
soil to level a patch *and* have it stay level for more that a couple of
months afterwards. Making the turf lie down flat again after it has been
stretched is pretty difficult too.

or simply rolling it (it is
heavy clay underneath)?

That will just compact the ground and make it more prone to water
logging. It would help with small bumps though.

The laziest way is to selectively top dress the low spots with a mix of
topsoil and sharp sand at every chance you get. Don't add too much at
once or you may kill the grass.

Regards,
--
Martin Brown