The answer is different depending on what is available at your exchange. Check at samknows and post either the link to the result page, or the exchange code.
Also it would help if you can find any figures of your actual usage of the 30GB. Most Entanet resellers have it available on their web site if you log into your account. (Or is it on the Entanet web site?)
Bob: Demon dialup >> Freeserve dialup >> BT Broadband >> Prodigynet >> Newnet >> O2 Standard.
Purple Cloud for domain, email and web space.
As I said then, the important thing is how much of that 30GB peak, and also how much of the 300GB off-peak you use.
Then for a good ISP you choose between IDNet, Zen and Newnet. Newnet if your total up and down of both peak and off-peak is less than 20GB. IDNet or Zen (who don't count upload) if your total peak and off-peak downloads are above 20GB.
Bob: Demon dialup >> Freeserve dialup >> BT Broadband >> Prodigynet >> Newnet >> O2 Standard.
Purple Cloud for domain, email and web space.