If you need new passports then now is the time to do it - I sent my daughter's passport form/photos etc off to Durham on Friday 7th for renewal. I got it weighed at the PO but didn't use check & send or pay for recorded delivery also, it was all on the form (I didn't submit anything online).
On Tuesday 11th I received a text stating that they had received the passport application and it would be 3 weeks.
Yesterday the new passport came in the post it had been processed on Monday 10th. As it was a renewal there should not have been any problems but I didn't expect it that quickly.