Lawn in need of help

Don't know much about lawns, but my mum bought some strips of turf from a garden centre a couple of weeks ago, & when she went to lay it, she found a large grub-thing (actually quite repulsive, & I don't mind caterpillars and things!). I googled lawn grub & there's a few types that come up - chafer beetle I think is one of them. Yellowing in patches can be a sign of grub damage. The little grubs bury themselves into the soil over the winter, & come up nearer the surface in late spring & damage the grass roots....apparently you should pull back a damaged area to check the soil underneath. They're large creamy coloured, crescent-shaped things with a darker head.
Might be worth checking?

Ok thanks very much for that, will certainly investigate as the lawn is looking a little worse for wear in places.

That's what the badger dig for in my lawn! They really are disgusting looking things, aren't they.