Birthday Party For An 11 Year Old Girl

I am turning 11 on the 21 of Janurary and need help finding one.All of your idead are great, but we need a cheap one because last year my party cost 155 pounds, and more for food,drinks,party bags, so please can you help with some CHEAP ENOGUH parties,as the last cost was TOO much!(Please post by the 19 of January, as my birthday is on the 21 but i will probably have the party, earlier than my b-day or later thank you!)