You can currently get a free trial and e.g. £125 of credit.
But I thought I would try a really cheap server £9->£10/month server to play around with - i.e. the "A0" instance, to see what was possible on a low spec vm.
But, when you create a new VM, the A0 build doesn't seem to be an option.
So I selected the cheapest option they gave me and tried to resize it.
But that gave an error saying something about it not being available due to premium storage.
So, what I had to do was delete that VM and all the associated resources. Then:
1. create a new VM, but make sure you choose "HDD" and not "SSD" for the non-premium storage.
2. choose the A1 size (not the A0 size at this point, that wouldn't come up).
3. wait for it to finish deploying and enter the running state
4. click on the VM and stop it, then wait for it to enter the deallocated state
5. click on "size" for the VN and resize it A0
An A0 instance is very low spec, so I wouldn't recommend running windows on it due to the UI-heavy interface of windows for administration. Better to run linux, or perhaps try the windows nano server.
Also, be careful of additional costs like storage, you may want to resize them down too, and with all these cloud services, there are plenty of other costs/limits for bandwidth etc. so take a look at your billing daily until you know what's what.
Currently, if you are on a free trial, then according to an MS post " you will not be charged for your free trial at any point unless you explicitly take the action of upgrading to a paid subscription. If you do nothing, the trial will just end without charging your card."