I had a new condensing combi boiler fitted 10 months ago(aparrently the only type of gas boiler you are allowed to have fitted these days) and noticed quite a saving in gas bills over that period, compared to my ancient back boiler even with the increase in gas prices. I'm also having cavity wall insulation fitted next week so hopefully that should help. I've no experience of economy 7 storage heaters though, sorry.
But, I was considering solar panels and storage heaters before we had the new boiler fitted as there were 50% government grants around at that time - don't know if there still is.
I'm beginning to wish i did with gas prices forever on the up, because even if i had borrowed the money, the loan repayments would have been not much more than my energy bills. Something worth considering maybe although even with the grants you'd be looking at around £8000+.