Dream house
30 year term - or whatever is longest term you could get. Santander will lend up to age 75, some older so depends on who the oldest borrower is.
Long term mortgage, 5 year fix, review at end of deal. Dependant on interest rates your monthly payments would be less than 1k as the capital owed remaining is less.
Shop around with mortgage lenders about 6 months prior, you can look at reducing the term then bit keeping the payments at the same amount.
Do this every 2, 3, or 5 years depending on the product you choose and your term could decrease by a year or so each time.