Put down a weed suppressing membrane first,this will keep the grass and other weeds from growing but will allow water to drain through and away.
Then I would suggest 10mm pea shingle.
These come in about 25kilo bags and two bags should cover an area of about three foot square at around one to two inches in depth. The bags range from about one pound fifty (pea shingle brown and fawn colour) to ten pound a bag (ALOT smaller bag) of various colours. Blue,green etc.
If the area has large bumps and dips it would be good to level it first,if their minor then don't bother unless you want perfection. Best of luck.

I don't know what the access is like to your front garden, but you may want to bear in mind that cats love using pea shingle as a toilet!

You can keep cats at bay by buying a gadget called Pestban.
They work by batteries or you can get the mains operated one.
I've got a couple and find them very helpful.
The way they work is by means of producing a high pitch sound uncomfortable to our feline friends.
It keeps them away! Regards.

thanks for your help may i ask do i have to dig the lawn or cut the grass or can i just put down the membrane, i am a complete novice when it comes to gardening so my back garden looks like a patchwork quilt

No need to dig up the grass,though you could cut it if it's very long to give a good base to start on.
What ever you do, the membrane will stop photosynthesis being able to proceed. No sunlight no growth and it will eventually die.
If you have to cut the membrane to fit the area, make sure that any pieces that have to be joined together overlap at least a foot otherwise through the procees of geotropism the leaves of the grass will find a way out. Good luck.

You can keep cats at bay by buying a gadget called a maxim machine gun, the police don't fully approve of their use in the suburbs, but who cares what the police think, come on City, it's only a horse, bite it. If you fetch the bags of shingle or whatever from the builder's merchants yourself keep in mind that anything much more than three 25kg bags in your boot at once can unsettle your suspension, unless you drive an old citroen.

If you have a builders merchants near you it is worth going and buying in bulk. They will deliver to your door and it is much cheaper. I bought a ton of gravel and it was less than £40 with delivery included. It was a nice size and was colourful enough.
Alison