I find SKY's service pretty good however I'm lucky that I get a stable 15mb connection. It's £10.00 per month for the unlimited broadband plus £14.50 for phone rental. A little out of your budget however SKY are offering the broadband completely free for the first 6 months. It's a 12 month contract. Over a year you'll pay £234 which works out at £19.50 per month so the 6 months free at the start means you'll actually come in under budget
It's not for everyone but worth a look.