I would do whatever I could do legally to get my kid into a great free secondary school
I didn't and that was the best decision I made.
OP, unless the other school is indeed very very bad and none of school years are likely to be there too, I would ignore your plans.
Being a landlord is a nightmare. Gas, electricity, EPC checks. Then you'll have to decide whether to pay for an agency or manage yourself. If using an agency, that's another 10% of fees, in addition to the 40% tax. Add the above checks, insurance, a buffer for repairs, will the 40% or so left even cover the mortgage? Would you be able to get a BTL mortgage? If not, will you get permission to rent?
Then you have to consider the sad facts of being a landlord. What happens if they stop paying? Sublet and get dodgy people in. Neighbours complaints, police involvement. What if they destroy your house. Then you have to be 100% certain you are doing everything by the books. A small tiny error protecting the deposit could see you having to pay them up to 3 months rent. How would you cope with the above?
Then you might find that they are not moving when you've given them notice to move back, what happens then?
Few schools are so bad that it would be worse on your daughter than having a stressed, helpless mum in financial difficulties. At worse, you can put her on the waiting list for the other school. Even if oversubscribed, most will be able to offer a place after a few months.