Of the four species of reptile occurring in Norfolk only two,the grass snake and slow worm are likely visitors to your garden.
The other two species, the adder and common lizard, are creatures of more open and undisturbed habitat such as heathland and only rarely visit gardens. Even then it is likely that the garden in question adjoins an area of suitable countryside.
If you wish to attract slow worms or grass snakes you will need to keep some areas of your garden undisturbed and uncultivated. Unkempt areas of long grass, wild areas of scrub and hedgerow with plenty of undergrowth and other nooks and crannies, such as provided by log piles, would be ideal. A compost heap is particularly useful since both slow worms and grass snakes will inhabit these either to feed on the abundant slugs and worms or to lay their eggs. A garden pond is also of great value to grass snakes because it provides ideal habitat for them to hunt frogs and newts.
If you are lucky enough to see any reptiles in your garden you should report sightings to the National Amphibian and Reptile Records Scheme (NARRS)
so that distribution and population trends can be monitored.