If you can afford the hall and food, you can provide the rest.
A two hour party sounds daunting.
First 15mins is really people arriving, have some music on. Then 1/2 hour of party games, you can lead them you really DO NOT need an entertainer. 1/2 an for food, another 1/2 an hour of games, and the last 15 minutes, party bags (even if its just cake!) and a general run about. It soon goes.
I did it last year and spent about £150. I borrowed some disco lights from the local pub, DH already had some amps (but you don't need BIG music, a Iplayer will suffice, but it depends on the size of the hall) and I borrowed a load of decorations from other mums. The food was simple, boggo standard part food, I make the 'puddings' (flapjack, brownies etc) and we just had big jugs of juice for the drinks.
It wasn't the best party I've been to, but the kids all had a good time and another parent said it was lovely to see an 'old school' proper party happening.
My only other tip is buy wine for when the kids are in bed because you'll need it.