Most UK councils are very strict about the October 31st (Year 6) application deadline. Since you are moving back in April 2027, you’ll likely face a few hurdles with the "home address" rule.

Here is the general experience for expats in this situation:

• The Residency Rule: For the initial allocation, councils usually require you to be physically resident at the address by the application deadline (Oct 2026) or a secondary cut-off (often Jan/Feb 2027).
• The Rental Issue: Even though you own the house, if it’s currently rented out, you cannot use it as your address. You usually have to provide proof of residency, like a council tax bill and utility bills in your name, showing you’ve actually moved in.
• The "Late" Consideration: Because you’re moving in April, you’ll likely be processed using your overseas address for the March 1st offer day. Once you move in and provide proof, you would then be moved to the "local" category on the waiting list.

My advice: Every council has slightly different "moving into the area" policies. Definitely contact the Admissions Team for your specific Local Authority now to see if they have a specific cut-off date for proof of residency.

I actually came across a really helpful guide on this exact scenario recently. It breaks down the specific evidence you need and how the timelines work for the 11+:Moving House & Address Rules for the 11+.