I don't know roses It's probably a good idea to take meter readings now, but it doesn't compel you to do anything with them. I'm in the same boat and am just planning on waiting and seeing what happens.
I'm expecting direct debits to not be taken, possibly for as much as a few months, if that happens, I'll mentally account for the fact that debt is building up so I have the money to pay for winter when I get established with a new supplier.
If you were with Avro, they will have a meter reading from the past month on record anyway, because they asked for readings every month, so its likely those readings will be available to your new supplier, so there's probably little opportunity to gain a little by maximising what you pay for at the Avro rate. Although you can always read any correspondence you get about readings carefully, to see if there is scope to save a little this way.
Martin Lewis was on the radio yesterday afternoon and I listened to it as a podcast.
www.bbc.co.uk/programmes/p02pc9xt/episodes/player
What's probably best for us all to do is just wait until we're established on a new tariff, which will probably be the new supplier's standard variable rate, which is currently cheaper than just about all the fixes until at least April.
If the current situation is just a blip, you don't want to fix now, because you'll be fixing at a high price. However, if it's the 'new normal' they SVRs will increase again next April and the fixes available then are likely to be even more expensive. So it's a gamble, but I'm probably just going to sit on whatever standard tariff I'm put on and keep an eye on things over winter, with a view to looking at it all again next April when the price cap is reviewed.