At worst you could just phone npower and make sure you’re on their best deal, then just phone them periodically to recheck.
In all honesty tho, switching supplier isn’t that bigger deal. The only thing that could put a spanner in the works when switching is if you’re in arrears to your current supplier then they can refuse the switch until you settle up. I’ve used MSE for years, I also use the Citz Advice Bureau one. It might be the same, but I don’t think so as there’s usually a few different deals on CAB v MSE. I sometimes look at Uswitch as well, just to see if there’s any different deals.
I’ve had mixed experiences with the new crop of small start ups, Eversmart was chaotic and just far too much hassle to manage, but very cheap deal which they tried to cut short until ofgem intervened (now gone bust I just noticed). Utility Point have been great.
On the MSE forum under Energy, there’s usually a post for every supplier titled “Add your feedback on energy supplier xxxxx”. If that post is on the front page and there’s pages and pages of feedback on that supplier, then you can probably assume it’s not good news.
So MSE is good, but faff free? well, it pays to put a bit of research effort in and you might have to make a few phone calls.