Hi Matt
As long as you have "Accrual dates" toggled on (in Settings>Configure system>Toggle features>Accounting), you can put an accrual date in the supplier's bill that would actually show in in say October's P&L
Alternatively, the traditional way to account for this in advance is via an "accruals" journal entry.
To do this you need an "Accrued expenses" or similar account code set up in "Other creditors" as well as enabling a Toggle feature called "Reverse on date journals" (also In Settings>Configure system>Toggle features>Accounting).
You create a journal entry (in Tools menu) with a debit to the purchase account code of £32K and a credit to the new accrued expenses code of £32K. You date it say 31 October to bring it into the October P&L and set a reverse date of say 1 November (ie the month you expect to receive the supplier's bill) .
In this way the November P&L will show a negative cost of £32K but a positive cost for the bill, which takes care of any difference.
If you wanted to actually grow the accrued expense over each month (June to October) you could set up a recurring journal entry (also in tools menu) for £6,400 to happen 30 June to 30 October.
Don't use the reversal date on it though as I don't think it works in recurring journals*, so leave the reverse date blank and then enter another journal 1 November debiting accruals £32K and crediting the cost code £32K.
*Tommy can someone check this and if relevant report as another defect?