Well this is what the UKBA (http://www.ukba.homeoffice.gov.uk/vi...ttlement/brp/#) say:
But call the public enquiry office you are going to and confirm about this. From a previous post of scottishbride about her sister-in-law's ILR application, she did the PEO but no biometrics were done.How do you enrol your biometric information and apply for a biometric residence permit?
If you make your application to extend your stay in the UK by post or online, we will send you a biometric notification letter after we have received your application. You should then enrol your biometric information at one of the post offices offering this service across the UK. For more information, see the Enrolling your biometric information - postal applications section.
If you make your application in person at one of our public enquiry offices or using our super premium service, you will enrol your biometric information on the same day. For more information, see the Public enquiry offices and Super premium service sections.