I'm with shell energy and they were pretty reasonable when I moved in to my new place in July. Am building up credit on a monthly Direct debit of £63 a month (it's a two bed flat and I'm the kind of person to put a jumper on before the heating)
No doubt it will go up
However it's worth bearing in mind that gas prices have FALLEN massively in the last three months. They aren't as low as they were but they are down a long way from the peak of the crisis a couple of months ago. Obviously that rise needs to feed through the system as some would have been purchased at a high price, but still..
Hopefully a mild winter will see prices fall back to normal
https://tradingeconomics.com/commodity/natural-gas