Welcome to the community and I'm really sorry to hear about your situation.
Pure Planet only provides 1 tariff, its variable so may go up or down providing clean energy at cost price with no mark up.
Pure Planet charges a membership fee which is the same as a standing charge to cover their infrastructure and business costs etc.
They have the facility option for E7 users to submit readings for both day and night but onto the one tariff.
That means your usage cost would be same as all other customers without E7.
Pure Planet are one of a few suppliers that provide this option.
I can advise after some research I did for a family member that Pure Planet was my first option / recommendation.
You can download their APP and or get a quote from their website.
Or utilise money saving expert to conduct a supplier price comparison... but best firm up the E7 option with each competitive supplier.
Just to advise that all communication is via the app, no call (costly) centre and replies are not instant, but very reliable.
Then theres always this community set up by Pure Planet, supported by us fellow customer members and the FaQ's.
In the first instance work out your total annual usage and gets some quotes so that you understand your options.
Look out for more feedback from other member/customers who will always chip in - I wish you all the best