Applying for Indefinite Leave to Remain: Will they take my passport?

I'm applying for settlement. Now I know that's going to be 6 months, probably more, and I'm fine being stuck in the UK until then.

My issue is that my passport expires in 4 months.

Obviously if they take my passport while they do this visa, there'll be problems.

I was just wondering if they do. Because if that were the case, it would mean a frantic journey down to London to renew it, as online passport renewals will take weeks.