What one is going to be best when i go to university I want it to be cheap to phone out to landlines and mobiles as I will mainly be phoning my friends. Also want it to be as cheap as possible to phone me.

Depending on the university network, VoIP may struggle.

For cheapest calling to mobiles, I'd used a Sipgate service and then sign up to 18185 and route calls via 18185, on the Sipgate service you dial the 18185 0808 access number and then the follow the prompts.

VoIP Stunt offers a good deal to landlines.

Sipgate offers for free an incoming number of any area-code, so you can have an area-code local to where most of your callers live, and not where you are if you so wished. As it is an 01 or 02 number then it's just the standard cost to call you as per a landline.

VoIP Stunt only cover major area-codes, so if you want an 01 or 02 number, you need to use an address in a Major area such as London, Birmingham, Manchester etc, otherwise you will get an 0560 number.